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LONGITUDINAL SECTION OF AMERICAN LOCOMOTIVE. 
By The Grant Locomotive Works, Paterson, New Jersey. 

Scale, f in. = 1 foot. 



-ri 







Plate III. 




^® 



PLAN OF AMERICANTLOCOMOTIVE. 
By The Grant Locomotive "Works, Paterson, New Jersey. 

Scale, | in. = 1 foot. 



CATECHISM 



OF THE 



LOCOMOTIVE 




BY 



MATTHIAS N. FORNEY, 

Mechanical Engineer. - 



Will be sent by mail, postage prepaid, on receipt of price $2.50. 

FREDERICK KEPPY, 

Scientific Book Publisher, 
No. 38 STATE STREET. BRIDGEPORT, CONN. 



' 



TJkof 




x 




Entered, according to Act of Congress, in the year 1874, by 

THE RAILROAD GAZETTE, 

In the office of the Librarian of Congress, at Washington. 



By Transfer 

0. C Public library 

MAR 2 9 



PREFACE. 



Books, like individuals, have their histories, and it 
seems but proper that in introducing them somewhat 
of their ancestry should be detailed. The present 
book originated in this wise : the publishers of the 
Kailroad Gazette procured a copy of the "Kate- 
chismus der Einrichtung und des Betriebes der Loco- 
motive," by Georg Kosak. As no English translation 
of this excellent little book was known to be in exist- 
ence, the editors of the above paper determined to 
translate it and adapt it to the American practice in 
the construction and management of locomotive steam 
engines, and republish it in their journal. The trans- 
lation was therefore made and submitted to the writer 
for revision and adaptation, according to the orig- 
inal intention. Before the latter was entertained, 
however, he had commenced writing an elementary 
treatise on the locomotive. In revising the first part 
of the translation of Mr. Kosak's book, it was found 
that the latter occupied only to a very limited extent 
the ground which the writer had " staked out " in his 
own incomplete plan. He therefore concluded to aban- 



iv Preface. 

don the original intention of " adapting" Mr. Kosak's 
work, and determined to rewrite it and make substan- 
tially a new book of it. For the " idea," however, and 
to some extent its plan, and for much valuable material, 
the author must acknowledge his indebtedness to Mr. 
Kosak. In some few cases the language of the trans- 
lator has been employed, in part or in whole, without 
quotation marks, but with an acknowledgment in a 
foot-note. A similar plan has also been pursued in 
using some other books. This was done to avoid cut- 
ting up paragraphs and sentences into fragmentary 
parts with numerous quotation marks. 

The following books have been consulted and used 
in writing the Catechism of the Locomotive : Heat 
considered as a Mode of Motion, by Prof. Tyndall; 
The Conservation of Energy, by Balfour Stewart; 
Railway Machinery, by D. K. Clark ; Treatise on the 
Locomotive Engine, by Zerah Colburn; Treatise on 
the Steam Engine, by W. J. M. Rankine ; Indicator 
Experiments on Locomotives, by Professor Bauschin- 
ger ; Richards' Steam Indicator, by Charles T. Porter ; 
Die Schule des Locomotivfuhrers, by J. Brosius and 
R. Koch ; Mechanics, by A. Morin ; The New Chemis- 
try, by J. P. Cooke, Jr. ; Combustion of Coal and the 
Prevention of Smoke, by C. Wye Williams ; A Trea- 
tise on Steam Boilers, by Robert Wilson ; Reports of 
the American Railway Master Mechanics' Association ; 
Link Valve Motion, by William S. Auchincloss, and 



Preface. v 

Emergencies and How to Treat Them, by Dr. Joseph 
W. Howe. 

For the title of the book an apology is perhaps 
needed, as the word Catechism is associated in nearly 
all persons' minds we will trust with early religious and 
theological instruction, and therefore a Catechism of 
the Locomotive is very apt to sound more ludicrous 
than scientific. The title of Mr. Kosak's book was 
adopted before it was determined to rewrite it, and it 
was afterwards not deemed best to change it. To 
those who are disposed to smile at it, the precedent of 
Mr. Bourne's excellent Catechism of the Steam En- 
gine is quoted, and if they will refer to Webster's 
Dictionary for the definition of the word " catechism," 
they will find that it means "an elementary book 
containing a summary of principles in any science 
or art, but appropriately in religion, reduced to the 
form of questions and answers, and sometimes with 
notes, explanations and reference to authorities," 
which is exactly what the present book is intended 
to be. 

To persons accustomed to, books and study, the 
catechetical form is very apt to seem cumbrous and 
awkward, but it has some very decided advantages in 
writing for those who have not acquired studious habits 
of thought. To such the question asked presents first 
a distinct image of the subject to be considered, so that 
the explanation or instruction which follows is much 



vi Preface, 

more apt to be understood than it would be if no such 
question had been asked. 

The author is indebted to Mr. D. B. Grant for the 
use of drawings from which most of the engravings of 
details of locomotives with which this book is illus- 
trated have been made, and to other locomotive build- 
ers, whose engines are illustrated in the full-page 
plates, for the drawings thereof. He has also received 
very valuable aid from Mr. Richard H. Buel, Mechan- 
ical Engineer; Mr. William Buchanan, Master Me- 
chanic of the Hudson River Railroad ; Mr. Frank D. 
Child, Superintendent of the Hinkley Locomotive 
Works ; and Mr. E. T. Jeffrey, Assistant Superinten- 
dent of Machinery of the Illinois Central Railroad. 

The object in writing the book was to furnish a 
clear and easily understood description of the princi- 
ples, construction and operation of the locomotive en- 
gine of the present day, a subject which is not con- 
cisely or adequately treated in any one similar book. 
If the author has succeeded in making what he has 
written plain to plain people, his aim will be fully ac- 
complished. 

No. 73 Broadway, New York. 



CONTENTS 



•-♦-• 

PAGE 

Preface m 

Introduction i x 

Part I. The Steam Engine 1 

II. The forces of Air and Steam 8 

III. On Work, Energy and the Mechanical Equivalent 

of Heat 22 

IV. The Slide- Valve 30 

V. The Expansion of Steam 47 

VI. General Description of a Locomotive Engine . 62 

VII. The Locomotive Boiler 71 

VIII. The Boiler Attachments 115 

IX. The Throttle- Valve and Steam-Pipes .... 155 
X. The Cylinders, Pistons, Guide-Rods and Con- 
necting-Rods 164 

XL The Valve-Gear 181 

XII. The Running-Gear 268 

XIII. Adhesion and Traction 319 

XIV. Internal Disturbing Forces in the Locomotive 328 
XV. Miscellaneous 335 

XVI. Screw Threads, Bolts and Nuts 341 

XVII. Tenders 349 

XVIII. Friction and Lubrication 358 

XIX. Combustion 365 

XX. The Resistance of Trains 406 



vm 



Contents. 



PAGE. 

XXI. Proportions of Locomotives 412 

XXII. Different Kinds of Locomotives 427 

XXIII. Continuous Train Brakes 442 

XXIV. Performance and Cost of Operating Locomotives 448 
XXV. Water-Tanks and Turn-Tables 451 

XXVI. Inspection of Locomotives 461 

XXVII. Running Locomotives 478 

XXVm. Accidents to Locomotives 509 

XXIX. Accidents and Injuries to Persons 533 

XXX. Responsibility and Qualification of Locomotive 

Runners 544 

List of Books for Mechanics, Locomotive Runners, Fire- 
men, etc., 550 

Plates 551 



APPENDIX 



I. Table of the Properties of Steam .585 

II. Table of Hyperbolic Logarithims 590 

III. Table of the Properties of Different Kinds of Fuel . 594 

IV. Table of the Resistance of Trains 596 

Index 698 



INTRODUCTION. 



The Catechism of the Locomotive is intended for 
a large class of readers, among whom are all kinds of 
railroad officers and employes, consisting of locomo- 
tive runners, firemen, and the many different kinds 
of mechanics employed in railroad shops and in the 
construction of locomotive and other kinds of railroad 
machinery and material. Besides these there are 
many amateur engineers, students, and persons inter- 
ested directly or indirectly in railroads, and a not in- 
considerable class who are always seeking information 
on all subjects whatsoever. It is evident, therefore, 
that the only way to adapt the book to all the classes 
for whom it is intended, was to make it so plain that 
the "wayfaring man" will have no difficulty in com- 
prehending it. It has therefore been written in as 
clear language as the writer could command, and the 
subjects presented are treated as simply and as plainly 
as his ability enabled him to do, and with the least 
possible employment of either scientific or practical 
technicalities. The only deviation from this plan will 



• 1 "-P 



x Introduction. 

be found in the use of algebraic symbols to designate 
arithmetical calculations. This was done to save 
space, and because it was thought that they could be 
explained so that even those without any knowledge 
whatsoever of algebra could easily comprehend them. 
To such as have no such knowledge the following ex- 
planation is given : 

Suppose it is necessary to add two numbers, say 
1,872 and 468. The calculation, if made arithmetically, 
would be thus : 

1,872 
468 



2,340 
This it will be seen occupies the space of several lines 
of print. If we want to express this calculation alge- 
braically, it can be done by simply writing the two 
numbers and placing the sign +, called plus, between 
the two, which indicates that they are to be added 
together, thus : 

1,872+468 
To indicate what the sum will be, or what the two 
added together will amount to, the sign = , called 
equal to, or the sign of equality, is placed after the 
two numbers and between them and the sum, thus : 

1,872+468=2,340, 
which can be read as follows : 

1,872 added to 468 is equal to 2,340. 
Now the only use of the algebraic signs + and = is 



Introduction. xi 

that they save time in writing and room in printing, 
and when persons become accustomed to their use they 
make plain a number of operations at a single glance, 
as will be shown hereafter. 

In the same way that the sign + means added to, 
the sign — means less or subtracted from, thus : 
1 ? 872 — 468=1,404, 

which is the same as though it was printed as follows : 
1,872 less 468 is equal to 1,404. 

The sign X means multiplied by, or is the sign of 
multiplication. Thus : 

1,872x468=876,096; 
that is, 

1,872 multiplied by 468 is equal to 876,096. 
The sign -V- means divided by, thus : 
1,872^-468=4. 

which means : 

1,872 divided by 468 is equal to 4. 

The same thing is expressed by putting a line 
under the dividend and writing the divisor under the 
line, thus : 

1,872 



= 4 



468 
These signs are combined in various ways. Thus, 
supposing we wanted to add 1,872 to 468 and then 
divide the sum by 117, it would be necessary, in order 



xii Introduction. 

to represent the arithmetical calculation, to do it as 

follows : 

1872 
468 



117)2340(20 
234 





Algebraically it would be stated thus 

1872+468 

= 20. 



117 

If you wanted to add 124 to the quotient 20 above. 

the calculation would be as follows : 

1872 
468 



117)2340( 20 
234 124 



144 

This operation could be expressed by writing it as 

follows : 

1872+468 

+ 124=144. 

117 

If we wanted to multiply the quotient 20 by 124 

we would simply put the sign X instead of + before 

124, thus : 

1872 + 468 

x 124=2480. 

117 



Introduction. 



xni 



The sign of subtraction or division can be used in 
the same way. 

With these explanations it is believed that any one, 
with nothing more than an ordinary knowledge of the 
four elementary rules of arithmetic, can understand all 
the mathematics contained in the following pages. 
A little explanation may also be needed of the method 
of representing machinery and other structures by 
mechanical drawings. 

If we want to represent the outside of any object, 
say an apple, we make a drawing of it as shown at A. 






Now if we want to show the inside of the apple, say 
the seeds and core, we can cut it in half and represent 

B 



xiv Introduction. 

it as shown at G, which is then called a section or sec-* 
iional view of the apple. If we represent it as it will 
appear if we are above it and looking down on it as 
shown at B, it is called a top view or plan. 

It is evident, too, that it might be desirable to show 
the arrangement of the seeds in the apple as they 
would appear if it was cut through in the other direc- 
tion, say on the line a b, fig. A, and as is shown at D. 
There are therefore two kinds of sections ; one G, in 
which the object is supposed to be cut through verti- 
cally, and therefore called a vertical section, the other 
when the object is supposed to be cut through hori- 
zontally, and therefore called a horizontal section, as 
shown at D. 

It is also evident that in looking at a locomotive 
or any other object, the appearance of the engine 
depends upon our position in relation to it. Thus, if 
we stand on the side of it, we see that part of 
the engine, and a drawing which represents the side, 
is therefore called a side view or side elevation. A 
drawing which represents a locomotive or other 
object as it would appear to us if we stood in 
front of it, is called a front view or front elevation , 
and a representation of the back part of any object 
as it would appear to us if we stood behind it is 
called a back view or back elevation. Plate I is a side 
view, Plate II a section, Plate III a top view or plan ;* 



* The boiler of the locomotive is supposed to be removed in Plate III, 



Introduction, xv 

the vignette in the title page is a front view and 
fig. 71 a back view of a locomotive. If the draw- 
ing is made as the object would appear if it was turned 
upside down, and we were looking at it from above, 
then it is called an inverted plan. 

It is obvious, too, that it is possible to make a great 
many different sectional views of nearly any object, 
especially of a machine. Thus, we could suppose a 
locomotive cut through vertically and lengthwise, as is 
shown in Plate II. Such a representation is called a 
longitudinal section. A locomotive could also be cut 
through crosswise, as shown in fig. 40, which is called 
a transverse section. It is of course possible to repre- 
sent a transverse section of a machine like a locomo- 
tive at a great many different points ; for example, it 
could be shown as though it was cut through the 
smoke-stack as in fig. 40, or through the boiler farther 
back, as the latter is shown in fig. 42. Usually when 
a section is shown through a cylindrical object like a 
smoke-stack or boiler, it is shown through its centre. 
If, however, this is not apparent from the drawing or 
engraving, it should be stated at what point it is sup- 
posed to be taken, thus the section D of the apple is 
on the line a b of fig. A, and the section O is on the 
line c d. 

In drawing sections, the parts which are supposed 
to be cut in two are usually shaded with parallel diag- 
onal lines drawn at equal distances apart, as shown in 



xvi Introduction. 

the sections of the apple at A and B. Sections are 
also sometimes represented with solid black surfaces, 
as in Plates II and III, and in the engraving of a 
pump in fig. 66. 

Objects which are behind others which are in front 
of them are often shown with dotted lines, so as to in- 
dicate their position. The seeds of the apple are thus 
indicated at A. 

It is also customary, in drawings of machinery, to 
take great liberties with the objects represented and 
to show them with parts removed or broken away, if 
their construction can thus be made plainer. It 
should be remembered that the purpose of drawings of 
this kind is not to give a pictorial representation of 
the object as it appears to the eye, but to make its 
construction and mode of operation apparent to the 
mind. In such drawings therefore all perspective is 
disregarded. It would lead us too far were we to ex- 
plain the reasons for this, and therefore readers must 
accept the assertion without the proof. 



CATECHISM OF THE LOCOMOTIVE. 



PART I. 
THE STEAM ENGINE. 

Question 1. What is the motive power employed in 
ordinary steam engines ? 

Answer. The expansive force of steam. 

Question 2. How is this expansive force of steam 
applied? 

Answer. It is applied by admitting it into a cylinder 

Fig.l. 




Scale | in.=l foot. 



A. Cylinder. 

B. Piston. 



G. Back Cylinder- Head. 



R. Piston- Rod. 

D. Front Cylinder-Head. 



(-4, fig. 1) in which a piston, B, is fitted so as to move 
air-tight from one end of the cylinder to the other. 
The steam, if admitted at c, will force the piston B to 



2 Catechism of the Locomotive. 

the opposite end* of the cylinder. When it has 
reached that end, if the steam is allowed to escape 
and a fresh supply is admitted to the cylinder through 
the opening d, it will move the piston back again. In 
this way, by alternately admitting steam at one end 
and exhausting it from the other, the piston receives 
a reciprocating motion, which is communicated to the 
outside of the cylinder by a rod, R, which is called 
the piston-rod, which works air-tight through an open- 
ing in one of the cylinder-covers, or cylinder-heads, as 
they are usually called. 



* In all ordinary locomotives, the cylinders are so placed that the head 
C through which the piston-rod works is behind, and the other head D 
in front. The two ends of the cylinder are therefore designated the 
front and back ends, respectively. 




-^ .>.a o o « a is 
^h Xt, J5 0) a) © a a q 



fl3o • eg jg « 

. o $<x > o 4>g 



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wEEgggS ^ 




G. Eccentric. 

K. K. Eccentric- Strap. 

L. Eccentric-Rod. 



The Steam Engine. 5 

Question 3. How is this reciprocating motion of the 
piston converted into rotary motion f 

Answer. By connecting the end of the piston-rod R 
(fig. 2) by another rod, E, called a connecting-rod, with 
a crank, P, which is attached to a revolving shaft, S. 
It is apparent that if the piston B is moved in the 
direction shown by the dart R, a rotary motion will be 
given to the crank in the direction of the dart N. 
When, however, the crank reaches the position shown 
by the dotted lines in fig. 5, it is plain that a force ap- 
plied to move the piston in either direction will no 
longer produce a rotary movement of the crank and 
shaft. The same thing will occur when the crank is in 
the opposite position, shown by the full lines. These 
two positions are called the dead-points of the crank. 

Question 4. How is the crank of an ordinary steam 
engine carried past the dead-points ? 

Answer. Stationary engines are usually provided 
with a large and heavy wheel, called a fly-wheel (F F, 
fig. 2) which is attached to the shaft S. This wheel 
receives a sufficient amount of momentum from the 
crank, while the latter is moving from one dead-point 
to the other, to carry it past those points. 

Question 5. How is the steam admitted to and ex- 
hausted from the cylinder f 

Answer. It is admitted through two channels, c, d, 
fig. 2, called steam-ways, cast in the cylinder. These 
ways terminate in a smooth flat surf ace, ff called 
the valve-seat. Their openings in the valve-seat are 
called steam-ports. Between them is another port or 
cavity, g, called the exhaust-port, which communicates 
with the open air. The form of these ports is 
long and narrow, as shown in fig. 4, which repre- 



6 Catechism of the Locomotive. 

sents a plan of them. Over these ports a valve, V, 
called a slide-valve, usually made of cast iron, with 
a cavity, H, on its under side, is fitted so that by 
moving it backwards or forwards it will alternately 
cover and uncover the two steam-ports. The valve 
and valve-seat are inclosed in a sort of box, II, fig. 
2, made of cast iron, called a steam-chest, into which 
steam is admitted from the boiler by a pipe, J. When 
the valve is in the position represented in fig. 2, the 
front steam-port is uncovered and the steam is admit- 
ted to the front end of the cylinder, and thus forces 
the piston towards the back end. If, when the piston 
reaches the back end, the valve be moved into the 
position shown in fig. 3, the back steam-port will be 
uncovered and steam will be admitted to that end of 
the cylinder. At the same time it will be observed 
that the aperture of the front steam-port c and that 
of the exhaust-port are both covered by the cavity in 
the slide-valve, so that the steam which was admitted 
to the front end of the cylinder can escape through 
the steam-port c into the exhaust-port, and thus into 
the open air. In this way, by moving the valve 
alternately back and forth, steam is simultaneously 
admitted first to one end and exhausted from the 
other, and vice versa. 

Question 6. How is the slide-valve moved so as to 
admit and exhaust the steam at the right time ? 

Answer. This is done by what is called an eccentric, 
which is a circular disc, G (fig. 6), the axis of which 
is not in the centre. The outside of the eccentric is 
embraced by a metal ring, KK, made in two halves, 
called an eccentric-strap. The eccentric is attached to 
the shaft by screws or keys, and revolves with it and 



The Steam Engine, 7 

inside of the eccentric-strap. To the latter is also 
attached a rod, L, called an eccentric-rod. It is obvi- 
ous from fig. 6 that if the eccentric revolves inside of 
the strap it will impart a reciprocating motion to the 
rod L. The eccentric, G, strap, K, and rod, L, are 
represented in fig. 2. Before describing their oper- 
ation, or rather their connection with the valve V, it 
is necessary to understand that usually the valve-seat 
is placed on top of the cylinder, in which position it 
is difficult to connect the eccentric-rod with the valve. 
For convenience, therefore, what is called a rocker, rr, 
is placed between the cylinder and the main shaft of 
the engine. This rocker has two arms attached to a 
shaft, s, and the two arms have a vibratory motion 
about it, as indicated by the dotted lines. The eccen- 
tric-rod L is attached by a pin to the lower arm of the 
rocker, and the valve is connected to the upper arm by 
the rod M, called the valve-stem, or valve-rod. It is 
obvious that as the shaft S and eccentric G revolve, 
a reciprocating or vibratory motion will be given 
to the rocker, which will be communicated to the valve 
by the valve-stem ; and it is only .necessary to fix the 
eccentric in the proper position on the shaft, in rela- 
tion to the crank and piston, to give the valve the re- 
quired motion for admitting and exhausting the steam 
to and from the cylinder at the right time. 



PART II. 
THE EOBCES OF AIR AXD STEAM. 

Question 7. What is meant by the pressure of the 
air f 

Answer. It is the pressure exerted "by the weight of 
the air on every point with which it is in contact. 
The globe of the earth is surrounded by a layer of air 
about 50 miles thick, and, like every other substance, 
the air possesses weight, and hence presses upon every 
object with which it is in contact. 

Question 8. How can it be shown that the air pos- 
sesses weight ? 

Answer. By weighing a flask when it is filled with 
air, and again when the air is exhausted from it. In 
the latter condition the weight of the flask will be 
found to be sensibly less than it was when full of air, 
showing that the air which the flask contained when 
it was first weighed increased its weight. 

Question 9. Why do we not feel this pressure on our 
bodies ? 

Answer. Because the air surrounds us on all sides, 
and presses just as much in one direction as it does in 
another, so that the pressures in different directions 
just balance each other, or are in equilibrium; but if 
you disturb this balance, for example, by sucking the 
air from a tube closed at one end, it will cling to your 
tongue; or if you take a thick piece of leather under 



The Forces of Air and Steam. 9 

ordinary conditions it will not adhere to anything, 
but if it be thoroughly wet and pressed hard against 
the surface of a smooth stone, so as to force out the 
air from under it, the stone, as nearly all school-boys 
know, can be lifted up if a string is attached to the 
leather ; or if the air be sucked out of a tube, one end 
of which is inserted in a liquid, the latter will be 
forced up the tube. These phenomena are due to the 
pressure of the atmosphere in the first case on one 
side of the person's tongue, pressing it against the 
mouth of the tube ; in the second, to the same pres- 
sure on the top of the leather, causing it to adhere to 
the stone ; and in the last, to the weight of the air 
pressing on the surface of the liquid, forcing it into 
the vacuum in the tube. 

Question 10. What is the amount of the pressure of 
the atmosphere, and how is it measured ? 

Answer. It is usually measured by the pressure on 
one square inch of surface, which at the earth's sur- 
face is 15 pounds.* If, for example, we have a cylin- 
der, A, fig. 7, with an air-tight piston, B, fitted to it 
whose area is just one square inch, if we exhaust the 
air through the tube G from the cylinder above the 
piston, the air will press against the under side of the 
piston so that, if no power is required to overcome its 
friction in the cylinder, the pressure of the air will 
raise a weight of 15 pounds. The pressure of the air 
varies, however, as you ascend or descend from the 
surface of the earth, because as you go up on a moun- 
tain or in a balloon the layer of air above you becomes 
thinner, and, therefore, its weight and consequent 

*In common practice it is generally taken at 16 lbs. per square inch, 
but the average atmospheric pressure is more accurately 14.7 pounds. 



10 



Catechism of the Locomotive* 




Fig 7 m Scale } 



15 POUNDS' 



pressure are diminished ; and as you descend, as in a 
deep mine, the layer is thicker, and its pressure con- 
sequently greater. 

Question 11. What is steam f 

Answer. Steam is water changed by means of heat 
into a gas. At every temperature there is formed 
from water, on its surface, vapor of which the clouds 
are formed at all seasons of the year. This change of 
water into vapor, or evaporation of water, takes place 
at low temperatures only on its surface, however. 
But if we heat water in a vessel to a temperature of 
212 degrees Fahrenheit, then the inner particles of 
the mass of water (lying on the heating surface of the 
vessel) are changed into steam, and rise to the surface 
in bubbles, which is the phenomenon we call boiling. 
It must not be imagined, however, that the visible 
cloud which escapes from a kettle or the exhaust-pipe 
of a steam engine is true steam. It is rather small 



The Forces of Air and Steam. 11 

particles of water, into which the steam has condensed 
through contact with the cold air. True steam is in- 
visible, as we may observe near the mouth of a kettle 
or the exhaust-pipe of an engine from which we know 
it is escaping. 

Question 12. If water is heated in an open vessel 
what occurs? 

Answer. It continues for some time to increase in 
temperature, and the evaporation becomes more and 
more rapid. At length bubbles of vapor break out 
and reach the surface, and the process of boiling 
or ebullition has begun. When this takes place 
the temperature of the water ceases to rise, and it 
remains stationary until all the water has boiled 
away, the only difference being that if the supply of 
heat be very great the process is very rapid, and if the 
supply of heat be small the process is very slow. The 
point at which ebullition commences is called the 
boiling-point. 

Question 13. On what does the boiling-point de- 
pend? 

Answer. Chiefly on the pressure on the surface of 
the water, but to some extent upon the purity of the 
water. Thus, boiling, which takes place at 212 de- 
grees under the ordinary atmospheric pressure, in 
lighter air, as on higli mountains, takes place at a 
much lower temperature than on lowlands, and so 
water boils in a glass tube from which the air has 
been exhausted by the warmth of the hand, that is, at 
92 degrees. 

Question 14. What is the pressure of steam which 
escapes from boiling water in an open vessel? 

Answer. It is exactly equal to the pressure of the 



12 Catechism of the Locomotive. 

atmosphere in which it is boiled. Ordinarily this is 
15 lbs., and the boiling-point 212 degrees ; but if we 
go up on a mountain where the atmospheric pressure 
is only 10 lbs. per square inch, the water will then 
boil at a temperature of 193.3 degrees, and the steam 
which escapes will have the same pressure as the 
atmosphere, or 10 lbs. per square inch. On the other 
hand, if we could go down into a mine where the 
atmospheric pressure was 20 lbs. per square inch, the 
water would not boil until it was heated to 228 de- 
grees, and the pressure of the escaping steam would 
then be 20 lbs. per square inch. 

Question 15. If water is boiled in an enclosed vessel 
like a covered tea-kettle or a steam boiler, what occurs ? 

Answer. The steam rises and fills the space above 
the water, and, if it cannot escape, increases in pres- 
sure. The temperature of both the water and the 
steam rises with the pressure, and will continue to do 
so as long as the heat is increased, or until the steam 
can escape or the vessel is exploded. The boiling 
point also rises as the steam pressure increases. 

Question 16. Is there any pressure which corre- 
sponds to the temperature of steam and water ? 

Answer. Yes. There is a fixed pressure for every 
temperature, when steam is in contact with water, 
and its pressure cannot be increased or diminished 
without at the same time heating or cooling the water, 
and the higher the temperature of the water the 
greater will be the corresponding steam pressure. 
Thus water at 212 degrees produces steam with a 
pressure equal to that of the atmosphere ; at 240 de- 
grees the steam will have a pressure of 25 lbs., or 10 
lbs. more than the atmospheric pressure ; at 281 de- 



The Forces of Air and Steam. 13 

grees a pressure of 50 lbs. ; and at 328 degrees, 100 
lbs. As this relation of pressure to temperature is 
fixed, if we know the one we can tell the other. This 
is true, however, only where the steam is in contact 
with water, when it is called saturated steam. If it is 
separated from water it may be heated to a higher 
temperature, and is then called superheated steam. 

Question 17. How is the pressure of steam meas- 
ured ? 

Answer. In the same way as that of the atmos- 
phere, — that is, by the force exerted on one square 
inch of surface. Thus if steam is admitted into the 
cylinder A, fig. 8, under the piston B, whose area is 
equal to one square inch of surface, supposing, as we 
did before, that no power is required to overcome its 
friction in the cylinder, if the steam thus admitted 
would just balance the atmosphere, its pressure would 
be equal to 15 lbs. If, besides overcoming the pres- 
sure of the atmosphere, it would raise a weight of 15 
lbs., then its pressure per square inch would be equal 
to 30 lbs. When the atmospheric pressure is included 
with that of the steam, we call it the absolute steam 
pressure. In ordinary engines, however, the steam 
must always overcome the pressure of the atmosphere, 
and therefore the only part of the pressure which is 
effective is that above, or by which it exceeds, the 
atmospheric pressure. For example, although the 
steam admitted under the piston in fig. 8 has an abso- 
lute pressure of 30 lbs. per square inch, yet it will 
only raise a weight of 15 lbs., because it must first 
overcome the pressure of the air on the other side of 
the piston. The pressure of the steam used in most 
stationary and in locomotive engines is, therefor* 
2 



14 Catechism of the Locomotive. 

measured by its pressure above the atmosphere. That 
is, if steam introduced under the piston in fig. 8 will 
raise a weight of only 15 lbs., we say it has a pressure 
of 15 lbs. per square inch ; if it will raise 50 lbs., its 
pressure is said to be 50 lbs. per square inch, and so 
on. The pressure of the atmosphere is disregarded, 
and all steam-gauges used on locomotives are gradu- 
ated in that way. In speaking of steam pressure in 
future, therefore, unless otherwise specified, we shall 
mean effective and not absolute pressure. 

Question 18. What is meant by the expansion of 
steam % 

Answer. In all gases a repulsion is exerted between 
the various particles, so that any gas, however small 
in quantity, will always fill the vessel in which it is 
held. Steam possesses this same property, and if 
placed in any vessel the particles in endeavoring to 
separate from each other will exert a force on all its 
sides. This force we call the steam pressure. To 
illustrate this we will suppose that the cylinder A in 
fig. 8 is half filled with steam of 30 lbs. pressure. If 
now the supply of steam is shut off, the steam in the 
cylinder will expand so as to push the piston upward, 
but with a somewhat diminishing force, the nature of 
which we will explain hereafter. 

Question 19. What is meant by the volume of steam ? 

Answer. It means the space which the steam occupies. 

Question 20. What is the proportion which exists 
between the volume and the pressure of steam ? 

Answer. If the temperatures remain the same they 
are inversely proportional to each other; 
that is, the one increases in the same proportion as 
the other diminishes. If we admit steam of 30 lbs- 



The Forces of Air and Steam. 



15 



Si 






Fig% 




Scale | 




pressure per square inch into the cylinder A, fig. 8, 
and then cut off the supply by closing the cock G 
and allow the steam in the cylinder to expand to 
double its volume by pushing the piston to the end of 
the cylinder, the steam pressure will then be only 15 
lbs. ; if it should expand to three times its volume its 
pressure would be only one-third, or 10 lbs. per square 
inch. This method for calculating the pressure of 
steam after it has expanded is correct only for the ab- 
solute and not for the effective pressures of steam. In 
order to ascertain the effective pressures of steam after 
expansion, it is only necessary to make the calculation 
with the absolute pressure and deduct the atmos- 
pheric pressure from the result. If, after being 
thus expanded, the piston be pushed down again 
so as to compress the steam into its original space, its 
pressure will again be 30 lbs., providing no heat has 
been lost in any way. 



16 Catechism of the Locomotive, 

Question 21. With a cylinder of any given stroke* 
how can we determine approximately the pressure of the 
steam after expansion for any given point of cut-off '?t 

Answer. By multiplying the absolute pres- 
sure PER SQUARE INCH OF THE STEAM IN THE CYL- 
INDER BEFORE IT IS CUT OFF, BY THE DISTANCE 
FROM THE BEGINNING OF THE STROKE AT WHICH 
IT IS CUT OFF, AND DIVIDING THE PRODUCT BY 
THE WHOLE LENGTH OF THE STROKE. TllUS, if we 

have a cylinder whose piston has a stroke of 24 
inches, if we cut off the steam at 8 inches, and have 
an absolute pressure of 90 lbs. in the cylinder, the 
calculation is as follows : 

— — =30 lbs. final pressure. 

If we cut off at 10, 12 and 15 inches, the final pres- 
sure would be 37J, 50 and 56% lbs., respectively. To 
get the effective pressure deduct the atmospheric pres- 
sure from this result. 

Question 22. What is the proportion between the 
volume of steam and that of the water from which it is 
formed f 

Answer. At the pressure of the atmosphere (15 lbs.) 
each cubic inch of water will make 1,610 cubic inches 
of steam. At double that pressure, or 30 lbs. absolute 
pressure, it will make a little more than half as much, 
or 838 cubic inches ; at four times, or 60 lbs. absolute 
pressure, 437 cubic inches, or a little more than a 
fourth as much as at the pressure of the atmosphere. 

*The stroke of a piston is the distance it moves in the cylinder, and in 
ordinary engines is always twice the length of the crank measured from 
center to center of the shaft and crank-pin. 

t The steam is said to be cut njf when the steam-port by which steam 
is admitted to the cylinder is closed by the valve. 



The Forces of Air and Steam. 17 

Question 23. Why is it that the quantity of steam at 
high pressures is somewhat greater than in inverse pro- 
portion to the pressure ? 

Answer. Because the boiling-point of water, as has 
already been explained, is higher as the pressure in- 
creases, and therefore the temperature of the steam 
produced at such pressure is also higher than at lower 
pressures ; and as all gases are expanded by heat, 
therefore the volume of steam at the higher pressures 
is somewhat greater than in inverse proportion to its 
pressure, on account of being somewhat expanded by 
its high temperature. To make this plain, if we take 
a cubic inch of water and convert it into steam of 
atmospheric pressure, its volume will be 1,610 times 
that of the water, and its temperature 212 degrees.* 
If we convert this quantity of water into steam with 
a pressure double that of the atmosphere, the volume 
of the steam will be 838 times that of the water and 
its temperature will be 250.4 degrees. If the volume 
of the steam were exactly inversely proportional to the 
pressure, the cubic inch of water at double the atmos- 
pheric pressure would make only 805 cubic inches of 
steam; but as the boiling-point at that pressure is 
38.4 degrees higher, the steam is expanded 33 cubic 
inches by the increase of its heat due to -the higher 
boiling-point. 

A table in the appendix gives the pressure, tem- 
perature and volume of saturated steam up to 300 lbs. 
absolute pressure. 

Question 24. What is meant by the condensation of 
steam ? 



* More accurately, 213.1 degrees, if we call the atmospheric pressure 
15 lbs., as we have. 

2* 



18 Catechism of the Locomotive. 

Answer. It is the reconversion of steam into water 
by cooling it, or depriving it of part of its heat. It 
has been shown that the temperature of water must 
be raised to a certain point to generate steam of a 
given pressure. If the process is reversed, and we 
deprive the steam of a part of its heat, some of the 
steam is then at once reconverted into water, or con- 
densed, and the pressure of that which remains will be 
reduced just in proportion as the heat is lost. When 
the temperature gets below 212 degrees under atmos- 
pheric pressure, all the steam will be condensed. As 
the useful work which steam can do in an engine is 
due to its pressure, which in turn depends on its tem- 
perature, any loss of heat will diminish its effective 
power. For this reason, all waste of heat from a steam 
engine should, as far as possible, be prevented. 

Question 25. How is the heat of the steam wasted or 
lost in an ordinary steam engine f 

Answer. It is wasted in three ways : first, by con- 
duction ; second, by convection ; and third, by radia- 
tion. 

Question 26. What is meant by these three terms? 

Answer. 1. By conduction is meant that phenom- 
enon which is manifested when we put one end of a 
metal bar two or three feet long into the fire and heat 
it. The heat is then gradually conveyed from one 
particle of the metal to that next to it until finally 
the end of the bar farthest from the fire becomes so 
hot that it cannot be touched. The heat is then said 
to be conducted through the bar. In the same way 
the metal of the boiler, pipes, cylinders and other 
parts of the engine becomes heated on one side, and 
the heat is thus conveyed to the outside of these parts. 



The Forces of Air and Steam. 



19 



2. The air with which they are surrounded then be- 
comes heated, and being then lighter than the cold 
air, it rises and is again replaced with air which is 
not heated. In this way the heat is conveyed away 
by the air, and this phenomena is therefore called 
convection. 

3. If an iron plate be placed in front of an ordinary 
grate fire three or four feet from it and exposed to the 
rays of heat from the fire, it will soon become so hot 
that you cannot bear your hand on it. If you place 
your hand between the iron plate and the fire you 
will find that only the side of your hand which is 
exposed to the fire will become hot, showing that the 
air between the plate and the fire is not nearly so hot 
as the plate soon becomes, and therefore that the heat 
is not conveyed to the plate by the air between it and 
the fire, but by the rays from the fire. This phenom- 
enon is called radiation. The same thing occurs from 
any hot body, as for example a coil of steam pipe for 
heating a room, a steam boiler or cylinder of an en- 
gine. 

Question 27. 7s there any difference in the conduct- 
ing and radiating power of different substances ? 

Answer. Yes, very great. The difference in the 
conducting power of wood and iron is shdwn if we 
place one end of a bar of each in the fire. The wood 
will be consumed without warming the bar more than 
a few inches from the fire, whereas the iron will soon 
become hot two or three feet from the fire. Owing to 
the difference in the conducting power of cotton and 
wool, we wear cotton clothing in summer and woolen 
in winter, because cotton allows the heat of the body 
to be conducted away from it, whereas woolen cloth 



20 Catechism of the Locomotive. 

prevents to a great degree this loss of heat. For the 
same reason, the venders of roasted chestnuts on our 
streets wrap them in a piece of blanket to keep them 
hot, that is, to keep the heat in ; and in summer we 
wrap ice in the same way to keep it cold, that is, keep 
the warmth of the air out. The wool, being a very 
bad conductor of heat, simply prevents the heat from 
being transferred from the inside to the outside, and 
vice versa. It is for this reason that steam boilers, 
pipes and cylinders are nearly always covered with 
wood, and sometimes with felt. 

The difference in the radiating power of various 
substances can be shown if we take a large thermom- 
eter and heat it up to the temperature of boiling water. 
If this thermometer is hung up in a room having the 
temperature of melting ice, it will lose heat in two 
ways, — first by heating the air which surrounds it, 
that is by convection, and also by radiation. In order to 
confine ourselves to the latter process, we will suppose 
that the chamber is a vacuum. If we first cover the 
bulb of the thermometer with a thin coating of pol- 
ished silver, and then ascertain how much heat it 
radiates in a minute, and then coat it with lamp- 
black, and repeat the same experiment, — that is to 
say, allow the thermometer at the boiling-point to 
cool for one minute in a vacuum chamber at the 
freezing-point, — it will be found that the thermome- 
ter loses much more in a minute when coated with 
lamp-black than it did when coated with silver, 
showing that much more heat is radiated from a 
surface covered with lamp-black than from polished 
silver. Generally it may be stated that polished 
metals radiate much less heat than surfaces which 



The Forces of Air and Steam, 21 

are not polished.* For. this reason, as well as for 

ornament, locomotive and other boilers and cylinders 
are usually covered with Russia iron or polished brass. 



* The account of the above experiment is copied from Balfour Stew- 
art's very excellent little book, "Lessons in Elementary Physics," of 
which, and. the same author's " Elementary Treatise on Heat," the 
writer has made frequent use. 



PART III. 

ON WORK, ENERGY, AND THE MECHAN- 
ICAL EQUIVALENT OF HEAT. 

Question 28. For what purpose are all steam en- 
gines used? 

Answer. They are used to produce motion, which is 
opposed by some resistance. Thus, if an engine is 
employed to raise grain from a railroad car to the top 
of a warehouse, it must produce motion, which is re- 
sisted by the weight of the grain ; if it is used to 
saw wood, it must give motion to the saw, which is 
resisted by the fibres of the wood ; a locomotive en- 
gine must produce motion of a train of cars, which is 
resisted by the air, the friction of the journals and the 
rolling of the wheels on the track ; if the locomotive is 
employed on a grade or incline, besides the frictional 
resistance referred to it must overcome that due to 
its own weight and that of the train, which is gradually 
lifted as it ascends the incline. In producing motion 
opposed by some resistance an engine is said to be do- 
ing "work." 

Question 29. Can this work be accurately measured? 

Answer. Yes ; but in order to measure anything we 
must first establish some accurate standard or unit of 
measurement. Thus we say a bar of iron is so many 
inches long, or a road is so many miles long. In like 
manner we speak of so many seconds, or minutes, or 
hours, or days, or years, when we speak of time. So 



On Work, Energy and Heat, 23 

it is necessary, in order to estimate or measure " work " 
in a strictly scientific manner, for us to fix upon some 
accurate standard or unit. In this country and in 
Great Britain the unit agreed upon for this purpose is 
the amount of power required to raise one pound 
one foot, and is called & foot-pound. If we raise one 
pound two feet we do two foot-pounds of work; if 
three feet, three foot-pounds, and so on. Again, if we 
raise a weight of two pounds one foot high, we like- 
wise do two foot-pounds of work ; or if we raise it two 
feet high, we do four foot-pounds, and so on. In 
order to determine the amount of work done, we must 

MULTIPLY THE MOTION PRODUCED (in feet) BY THE 
RESISTANCE (in pounds), AND THE RESULT WILL BE 
THE WORK DONE IN FOOT-POUNDS. 

Question 30. How many foot-pounds of work are 
performed in a pile-driving machine in raising a weight 
of 1,200 lbs. 24 feet? 

Answer. 1,200x24=28,800 foot-pounds. 

Question 31. When this weight is raised, is the force 
which was exerted in raising it annihilated or lost ? 

Answer. No; because the weight has the capacity 
of doing an equal amount of work when it falls, from 
the momentum* it acquires in falling. This power of 
doing work which it acquires in falling is called energy. 
Now, although the weight has no motion-producing 
power when it is raised to the top of the machine, yet 
obviously such action is then possible which when it 
rested on the earth was not possible. It has no en- 
ergy as it hangs there dead and motionless; but 
energy is possible to it, and we might fairly use the 



* Momentum is not a very exact term, but is used here because it or- 
dinarily conveys the idea we wish to express. 



24 Catechism of the Locomotive. 

term possible energy to express this power of motion 
which the weight possesses,* and which is therefore 
called potential energy. As soon as the weight is al- 
lowed to fall it acquires a greater velocity the farther 
it falls, and its potential energy tlms becomes and is 
called actual energy. 

Question 32. How do we explain such phenomena 
as the heating of a car-axle while turning under a car, 
the heating of brake-blocks when the brakes are applied to 
car-wheels, the heating of an iron rod by hammering, and 
of a turning tool when cutting a piece of metal ? 

Answer. All of these phenomena are due to the fact 
that the actual energy of motion is converted into heat, 
as has been repeatedly proved by many able and in- 
genious investigators and experiments. 

Question 33. When the iveight of the pile-driver 
falls, is its energy also converted into heat ? 

Answer. A part is expended in compressing the 
material into which the pile is driven and in overcom- 
ing the friction of the earth against the pile, each of 
which efforts develops heat, and another portion is 
converted into heat by the impact or blow of the fall- 
ing weight on the head of the pile. 

Question 34. Is all energy convertible into heat and 
heat into energy ? 

Answer. Yes. Science has demonstrated very clearly 
that they are mutually convertible. 

Question 35. Has it been ascertained how much heat 
is equivalent to one foot-pound of 2cork? 

Answer. Yes ; it has been found, from the most 
carefully-made experiments that the amount of heat 



* Tyndall's " Heat Considered as a Mode of Motion." 



On Work, Energy and Heat. 



25 



which is required to raise the temperature of one 
pound of liquid water by one degree of Fahrenheit* 
is equivalent to 772 foot-pounds of work. It must be 
remembered that this is the theoretical equivalent of 
heat, and that only a very small proportion of this 
amount of work is ever realized from the heat devel- 
oped by the combustion of fuel. 

Question 36. If, then, heat is convertible into work 
and work into heat, can the transmutation of the heat of 
the steam in the cylinder of an engine into work, and the 
reverse process, be explained f 

Answer. Yes. Take a cylinder, fig. 9, and, in or- 
der to make the conditions of the experiment as 
simple as possible, imagine it to be placed in 
a vacuum. Now let saturated steam be admit- 
ted under the piston so as to fill the cylinder 
half full at an absolute pressure of 100 lbs. If we 
will allow this steam to expand to double its volume 
and raise the piston without doing any 
work, and then repeat the experiment 
with a load of 50 pounds on the pis- 
ton, whose area is one square inch, 
it will be found that the temperature 
of the steam is sensibly less, after 
lifting the weight, than in the previ- 
ous experiment, in which it expanded 
without doing work, showing that 
part of the heat was abstracted from 
the steam by doing work, or, in other 
Fig. 9. words, was converted into work. If 

Scale | in.=l foot. 




* Thermometers are divided into different scales. The one called the 
Fahrenheit scale, after its originator, is the one ordinarily used in this 
country. 

3 



26 Catechism of the Locomotive. 

then, after the steam has expanded and lifted the 
weight, we press the piston down so that the steam 
under the piston is compressed to its original volume, 
we shall find that its temperature is the same as be- 
fore, as the work done in compressing it is converted 
into heat. In these experiments it is assumed that 
there is no friction of the piston, nor loss of heat from 
radiation or conduction. The same phenomena can 
be observed in machines used for compressing air, 
which is heated to so high a temperature when it is 
compressed that it is necessary to cool the cylinders 
of such machines by circulating a current of cold 
water around them. 

Question 37. What practical relation is there be- 
tween the convertibility of heat into ivork, and the con- 
ducting and radiating properties of different substances 
explained in answer to Question 27 ? 

Answer. The fact that heat is only another form of 
energy, or "the power of doing work," indicates that 
its loss by conduction or radiation lessens that power 
just as much as or more than the loss or waste of coal 
would, and therefore every effort should be made to 
protect the different parts of engines from loss of heat 
by covering them with substances which conduct or 
radiate very little heat. Care should also be taken to 
exclude cold air from circulating in contact with these 
parts, and excepting for supporting combustion, the 
nature of which will be explained hereafter, it should 
be excluded from the heating surface of boilers. 

Question 38. What is meant by the term latent 

HEAT OF EVAPORATION? 

Answer. By latent heat is meant that heat which 
apparently disappears when water or other liquids are 



On Work, Energy and Heat. 27 

vaporized. Thus, it is found that if any quantity of 
water is converted into steam at any pressure, it is 
necessary not only to heat it to a temperature equiv- 
alent to that of the steam, or to the boiling-point, but 
after it has reached that temperature an additional 
amount of heat must be added in order to keep up the 
process of boiling. Notwithstanding this addition of 
heat to the water, the temperature of the steam pro- 
duced will not be higher than that of the boiling 
water, thus showing that a considerable quantity of 
heat is absorbed, the only effect of which is to change 
the water into a gas or steam. This apparent disap- 
pearance of heat can be shown if we take a pound of 
boiling water whose temperature is 212 degrees and 
mix it with a pound of ice-cold water at 32 degrees. 
The result will be a mixture of two pounds of water 
of a mean temperature of 122 degrees. If now we 
convert a pound of water into steam at atmospheric 
pressure, the steam will heat 6.37 lbs. of ice-cold 
water up to 122 degrees, showing that a pound of 
steam at atmospheric pressure contains over six times 
as much heat as a pound of water of the same tem- 
perature as indicated by a thermometer. A similar 
apparent disappearance of heat occurs when other 
liquids are evaporated, and when ice or any other 
solid is converted into a liquid. 

Question 39. What is the explanation of these phe- 
nomena ? 

Answer. The exact reasons which will explain them 
fully are probably not yet clearly understood, but it is 
at least extremely probable that when any substance 
is changed from a solid to a liquid, or from a liquid to 
a gaseous condition, "a large portion of the heat is 



28 Catechism of the Locomotive, 

spent in doing work against the force of cohesion."* 
The particles of solid bodies, as we know, are so united 
that it requires more or less force, according to the 
nature of the substance, to tear them apart. Now we 
can conceive that the heat is changed into a form of 
energy, and in that condition resists this attraction of 
the particles to each other, and that being thus trans- 
formed it has lost the capacity of expanding the mer- 
cury in the thermometer. A similar effect takes place 
when a liquid is converted into a gas. In the former 
condition the particles move freely about each other 
and have little or no attraction for each other, but 
when it becomes a gas they have a repulsion from 
each other. The heat is thus converted into the 
energy of repulsion, and therefore is in reality no 
longer in the condition of heat and consequently does 
not affect the thermometer. We can illustrate this by 
supposing that by using steam heat is converted into 
work by raising the weight, or drop as it is called, of 
a pile-driving machine. When the weight is raised 
to the top of the guides from which it falls, although, 
as already explained, the heat is converted into poten- 
tial energy, yet if we attached a thermometer to the 
drop we would not find that it was any warmer than 
before the drop was raised. If it were possible to 
make an instrument sufficiently sensitive to indicate 
an instantaneous change of temperature in the weight 
while falling, we would not find any increase of its 
temperature at the instant it had acquired its greatest 
momentum and just before it struck the object under 
it, although its potential energy would at that instant 



Balfour Stewart on the Conservation of Energy. 



On Work, Energy and Heat. 29 

be converted into actual energy of motion. If, how- 
ever, the weight should strike an unyielding object, 
its actual energy would at once be reconverted into 
heat, which our thermometer would indicate. The 
phenomenon of what is called latent heat of evapora- 
tion seems to be very similar to that described — the 
heat when the water is changed from a liquid to a 
gaseous condition is transformed into energy, which, 
as already stated, has no effect upon the mercury of 
the thermometer. 

Question 40. What is meant by the total heat of 
steam ? 

Answer. The " total heat of steam" is a phrase used 
to denote the sum of the heat required to raise the 
temperature of water from some given point up to the 
boiling-point due to a given pressure, and of the heat 
which disappears in evaporating one pound of water 
under a given pressure (or latent heat of evaporation?) 
Thus the latent heat of one pound of steam at atmos- 
pheric pressure (14.7 lbs.) is 966.1 units ; and 212 
units of heat are necessary to raise water from zero to 
the boiling-point; therefore the total heat counted 
from zero of steam of atmospheric pressure is 1,178.1 
units. At 100 pounds . absolute pressure the latent 
heat is 885.5 . and the sensible heat 327.9 degrees ; 
therefore the total heat measured from zero is 1,213.4 
units. 

3* 



PART IV. 
THE SLIDE-VALVE. 

Question" 41. What are the essential conditions 
which a slide-valve must fulfill in governing the admission 
and exhaust of steam to and from the cylinder of an or- 
dinary engine ? 

Answer. 1. It must admit steam to one end only of 
the cylinders at one time. 2. It must allow the steam 
to escape from one end at least as soon as it is admit- 
ted to the other end ; and 3, it must cover the steam- 
ports so as not to permit the steam to escape from the 
steam-chest into the exhaust-port. 

Question 42. What was the first form of slide-valve 



Answer, That represented in fig. 10. The smallest 




Scale 3-16 in. = 1 inch, 
movement of this valve either way opens one of the 



The Slide Valve. 31 

steam-ports for the admission of steam and puts the 
other in communication with the exhaust-port. By 
cutting a piece of ordinary writing paper to the 
form of the section of the valve, and moving it on 
the line ff, the action of the valve will be clearly 
shown. 

Question 43. How was the admission and escape of 
the steam effected by this valve f 

Answer. In order to explain this clearly, a series of 
diagrams will be necessary. Before referring to 
them, however, it should be explained first that the 
motion of an eccentric is exactly the same as that of 
a small crank. It is in fact a crank with a crank-pin 
whose diameter is very much enlarged. In the dia- 
grams, figs. 11 to 25, the eccentrics will therefore be 
represented as small cranks, and most of the other 
parts by their centre-lines and points only, so as to 
make the diagrams as simple as possible. The dimen- 
sions selected for these illustrations are for the cylin- 
der 16 in. diameter and 24 in. stroke, and a connect- 
ing-rod 7 ft. long. The steam-ports are 1£ in., the 
exhaust-port 2\ in., and the metal or bars between 
them, which are called bridges, are 1^ in. wide. The 
eccentric produces a lateral movement of 3 in., which 
is called its throw. In fig. 11 the piston is at the be- 
ginning of the backward stroke. The valve is then in 
the centre of the valve-face, and the eccentric is con- 
sequently at half- throw. The slightest movement of 
the crank in the direction of the dart N will move the 
eccentric enougli to open the front steam-port to the 
steam and the back one to the exhaust. In fig. 12 
the piston is represented as having moved 4 in. of its 
stroke ; the valve has then partly opened the front 



Plate I. 




a a 4 s e PR. 

AMERICAN LOCOMOTIVE. 
By The Grant Locomotive "Works, Paterson, New Jersey. 

Scale, | in. = 1 /o<tf. 



Catechism of the Locomotive. 



Fig. JL 



/' "N 



w- 








%i4. 




f 



~" t-^ 




* — *?► 



Scale i in. = 1 foot. 



The Slide Valve, 



33 



Fig.24 






H« 




F^.£3 




i^y.22 







Fig. 21 




f 







Fig. 20 







K.y 









Fig. 19 





Fujl18 



£ tN 



Scale j in. = 1 foot. 



34 Catechism of the Locomotive, 

steam-port, and the other one is open to the exhaust. 
In fig. 13 the piston has moved 8 in. of its stroke, and 
the ports are now wide open, the front one to the 
steam and the hack one to the exhaust. In fig. 14 
the piston has moved 12 in., or is at half-stroke, and 
the valve has then moved as far as it will in that di- 
rection. In fig. 15 the piston has moved 16 in. and 
the valve has begun to return. In fig. 16 the piston 
has moved 20 in., and the valve has nearly closed the 
front port to the steam and the other to the exhaust. 
In fig. 17 the forward stroke is completed, and both 
ports are closed by the valve. Figs. 18, 19, 20, 21, 
22 and 23 represent the piston and the valve on the 
return stroke in the positions corresponding with 
those described for the backward stroke. 

Question 44. Is there any other method by which the 
motion of a valve can be represented by a drawing ? 

Answer. Yes, by what are called motion-curves. It 
is, however, difficult to explain these clearly, and as 
they are purely imaginary, it is difficult to understand 
their nature and purpose. Close attention will there- 
fore be required to the following description : 

We will suppose, in the first place, that the Ymeff, 
fig. 25, represents the valve-face, c and d the steam 
and g the exhaust-port, drawn to a larger scale than 
in the preceding figures. We will now draw the valve 
H in the position represented in fig. 11, where the 
piston is at the beginning of the stroke. In order to 
show the valve in the position represented in fig. 12, 
where the piston has moved 4 in. of the stroke, we 
will draw a line 4-20, four inches below and parallel 
to ff, and extend the lines, representing the edges 
of the ports c, d and g, downward. On the horizontal 



The Slide Valve. 35 

line 4-20 we will now draw the edges »', r, i\ r , of the 
valve in the same position in relation to the port c 
that it has in fig. 12. We will then draw another 
horizontal line, 8-16, eight inches below ff and par- 
allel to it, and on this represent the valve in the posi- 
tion shown in fig. 13. In the same way we will draw 
lines 12, 16, 20 and 24 in. below ff and draw the 
valve on each one respectively in the positions shown 
in figs. 14, 15, 16 and 17. The distance between the 
lower line 24-0, and ff will then represent the 
stroke of the piston, or 24 in. If now we begin from 
the edge h of the valve on the line ff and draw a 
curve, h i j k I m n, through the same edge of the 
valve, represented on each of the parallel lines below, 
the curve will indicate the position of the valve in re- 
lation to the steam-port c at each point of the stroke. 
To illustrate this, suppose we draw lines 1-23, 2-22, 
and 3-21, one inch apart and parallel toff and be- 
tween it and 4-20. They will then represent the po- 
sition of the piston after it has moved 1, 2 and 3 in. 
from the beginning of the stroke, and where they in- 
tersect the curved line will be the position of the edge 
of the valve when the piston has moved 1, 2 and 3 in. 
of the stroke. The curved line will in fact represent 
the position of the valve at any point of the stroke be- 
tween these lines. Other horizontal lines, 5-19, 6- 
18, etc., can be drawn to represent every inch of the 
rest of the stroke. The curve line h i j k I m n, or 
motion-curve as it is called, will then show the exact 
position of the edge of the valve and of the width of 
the opening of the steam-port during the whole stroke. 
From it we see that the valve opens the port c for the 
admission of steam simultaneously with the move- 




Scale 6-16 in. = l ineii. 



The Slide Valve. 37 

ment of the piston, and when the latter has made one 
inch of its stroke the port c is half open. At 4 J 
inches of the stroke the port is wide open,* and at 19| 
inches it begins to be closed, but is not completely 
closed until the end of the stroke. 

Similar motion-curves, such as h' i' j' h' V m' n\ 
(represented in fig. 25) can be drawn to represent the 
position of the other edges of the valve, and also for 
the return stroke. The latter are shown in dotted 
lines. If we follow the curve h' i' j' k' V m' n\ 
which represents the position of the edge of the valve 
h' which governs the exhaust from the back end of 
the cylinder, we see that the port d is opened and 
closed to the exhaust simultaneously with the opening 
and closing of the port c for the admission of steam to 
the front end of the cylinder, and that they both re- 
main open until the completion of the stroke. 

The width that the ports are opened by the valve is 
thus ascertainable from these diagrams, for any point 
of the stroke, and in fact can be seen at a glance. 
By the aid of such motion-curves, the movement of 
slide-valves can therefore be analyzed more perfectly 
than is possible without them. 

Question 45. What were some of the disadvantages 
of valves, like that shown in fig. 10, and which are shown 
by the motion-curves in Jig. 25. 

Answer. The free admission of the steam until the 
completion of the stroke by the piston was hurtful to 
the machinery, as it co-operated with the momentum 
of the piston and its connections in producing undue 

* By cutting a paper section of the valve and placing it on the dia- 
gram in each position named, it will probably help the reader to under- 
stand the movement of the valve more and the nature of the motien- 
curves. 



38 Catechism of the Locomotive, 

strains in the working parts. The steam then escaped 
from the cylinder without expansion, so that much of 
its useful energy was lost. The steam was not al- 
lowed to escape from one end of the cylinder until it 
was admitted at the opposite end, and as the process 
of exhausting it occupies some time, there was always 
more or less back pressure until all the exhaust steam 
was expelled from the cylinder. In practice, the im- 
perfections of the valve-gear frequently delayed the 
opening of the ports, both for admitting and exhaust- 
ing steam, until after the commencement of the stroke 
of the piston.* 

Question 46. How may some of these evils be over- 
come? 

Answer. By moving the eccentric forward on the 
axle so that the motion of the valve is advanced to the 
same extent, and the admission and exhaust of the 
steam will occur a little before the completion of the 
stroke of the piston. In this way the steam is ad- 
mitted into the cylinder so as to act as a cushion to 
receive the momentum of the piston, and some time is 
given to the exhaust steam to escape, before the re- 
turn stroke. 

Question 47. What is meant by lead? 

Answer. By lead is meant the width of the opening 
of the steam-ports at the beginning of the stroke of 
the piston. On the steam side of the valve it is called 
outside lead; on the exhaust side inside lead. In fig. 
26 the opening h of the steam-port is the outside lead 
and h' the inside lead. 

Question 48. What is meant by the travel of a valve ? 

Answer. By the travel we mean the motion of the 

* D. K. Clark's " Railway Machinery." 




Scale 3-16 i.i. = xincb. 



40 



Catechism of the Locomotive. 



valve back and forth, or in other words its stroke. If 
the arms of the rocker are of the same length, the 
travel of the valve is equal to the throw of the eccen- 
tric. For the preceding illustrations we have selected 
an eccentric with three inches throw, which is the 
travel of the valve. 

Question 49. How is the steam made to work expan- 
sively with a slide-valve f 

Answer. By giving the valve what is called lap. 
That is, by allowing the edges of the valve when it is 
in the center of the valve-seat to overlap the edges of 
the steam-ports, as shown in fig. 27. Where this over- 
lap, L L, is on the outside of the valve, it is called 




Scale 3-16 in. = 1 inch. 

outside lap ; when on the inside, 1 1, inside lap. When 
a valve has lap, those portions of the face* h, i, -and 
p, q, which cover the steam-ports, being wider than 
the ports, therefore occupy some time in moving over 
them, during which time the steam is enclosed in the 
end of the cylinder, as there is then no communication 
either with the steam-chest or the exhaust-port. This 



* The valve-face is the surface of the valve in contact with the valve- 
seat. 



The Slide- Valve. 41 

action is shown very clearly by the motion-curves in 
fig. 26. The valve in this case has £ inch lead. At 
4J inches of the stroke of the piston the valve has 
moved as far as it will go in that direction, and the 
steam-port has its maximum width of opening. From 
that point the valve will begin to close the steam- 
port, and at 14^ inches of the stroke the port will be 
entirely covered, and the steam therefore be cut off. 
The port will remain closed until the piston has 
moved 21f inches, when it will be observed from the 
motion-curve r s t u v w x, that the port c is opened 
to the exhaust and the steam escapes, or, as it is tech- 
nically called, the release takes place. From the time 
the steam is cut off to the time it is released, it works 
expansively in the cylinder. 

Question 50. What relation is there between the 
amount of lap* and the degree of expansion ? 

Answer. The greater the lap with any given travel, 
the shorter will be the period of admission of steam, 
and, consequently, the more time and space for ex- 
pansion. 

Question 51. What is the effect of inside lap f 

Answer. It delays the release of the steam. Thus 
in fig. 26 the valve has £ in. inside lap. The motion- 
curve r s t u v w x shows that the release takes 
place during the back stroke at 21| in. If now there 
Vas no inside lap, the dotted line y, x would represent 
the exhaust edges of the valve, and the release would 
then occur somewhat earlier, or at 21 in._ For this 
reason no inside lap is usually given to valves for en- 
gines which run at high rates of speed, as it allows 
too little time for the steam to escape. In fact, in 



* In speaking simply of lap, outside lap is always meant. 



42 



Catechism of the Locomotive. 



some cases, what is called inside clearance is given to 
the valve ; that is, the valve as shown in fig. 29, when 
it is in the middle of the valve-face, does not entirely 
cover the steam-ports. The effect of this is just the 
reverse of that produced hy inside lap; that is, it 
causes the release to occur earlier in the stroke. 




Scale 3-16 in. = 1 inch. 

Question 52. With the same outside lap, what is the 
effect of changing the travel of the valve ? 

Answer. By increasing the travel, the period of ad- 
mission is increased and that for expansion lessened ; 
and by reducing it, the admission is lessened, and the 
degree of expansion is increased. This is shown by 
the motion-curves in fig. 28, in which the same valve 
and ports are represented as are shown in fig. 26, but 
the valve has a travel of 5 instead of 3 inches. The 
valve also has the same lead. By following the mo- 
tion-curve h i j k I m n, it will be seen that the 
steam is thus admitted up to 20^ inches of the stroke 
ef the piston, and the period of expansion, as com- 
pared with that in fig. 26, is correspondingly lessened. 
It will also be seen by comparing fig. 26 with fig. 28 
that with the short -travel of the valve the ports are 




Scale 3-16 in. =1 Inch. 



44 Catechism, of the Locomotive. 

not opened so wide as they are when tho travel is in- 
creased. This evil is practically obviated, however, 
by making the ports so long that with a compara- 
tively small opening they will still have area sufficient 
to admit enough steam to fill the cylinders, and it is 
known that an opening less than the whole area of the 
steam-ports is sufficient to facilitate the passage of 
steam into the cylinder. 

Question 53. How is the exhaust affected by lap and 
lead'? 

Answer. The steam is released earlier in the stroke 
in proportion as the amount of outside lap and lead is 
increased, but the steam-port is also closed to the ex- 
haust, or compression, as it is called, begins earlier with 
lap and lead than without. Thus, in fig. 25, it will be 
seen that at the beginning of the stroke both ports 
are entirely closed ; in fig, 26, however, in which the 
valve has both lap and lead, the port d is nearly wide 
open at the beginning of the stroke, and by following 
the motion-curve r s t u v w x, which represents 
the position of the exhaust edge of the valve, it will 
be seen that the steam was released from the port c 
before the piston had completed its stroke, or when it 
had still nearly 3J inches to move. In fig. 25 the port 
c is not opened to the exhaust until the commence- 
ment of the stroke, but it remains open to its comple- 
tion, whereas in fig. 26 it is closed, or compression 
begins, at 18 inches of the return stroke, as shown by 
the dotted motion-curve. 

Question 54. How does the action of the connecting- 
rod influence the motion of the valve in relation to the 
piston ? 

Answer. By delaying the movement of the crank in 



The Slide- Valve. 45 

the backward stroke of the piston, and accelerating it 
in the forward stroke. This will be best explained by 
reference to fig. 14, in which the piston is represented 
in the center of the cylinder, or the middle of the 
backward stroke. If now we take a pair of dividers 
set to a length equal to that of the connecting-rod, 
and from the center, f, describe an arc of a circle, a b, 
from the center of the shaft, and through the lower 
half of the circle which represents the path of the 
crank-pin, we will find that the point of intersection, 
a, falls short of the vertical line, c d, and that the 
crank-pin has not made quite one-quarter of a revolu- 
tion while the piston was moving through the first 
half of the backward stroke. By referring to fig. 21, 
in which the piston is again in the middle of its stroke, 
but is moving forward, and by describing another arc 
of a circle, b a, from the center of the shaft and inter- 
secting the path of the crank-pin, it will be seen that 
the latter has moved more than a quarter revolution, 
while the piston has made the first half of the forward 
stroke. Owing to this angularity, as it is called, of 
the connecting-rod, the crank-pin is behind the piston 
during its backward stroke and ahead of it during the 
forward stroke. As the valve is moved by the eccen- 
tric, and it in turn by the shaft and crank, any irreg- 
ularities of the latter are of course communicated to 
the valve. We therefore find, by referring to fig. 26, 
that the point of cut-off occurs during the backward 
stroke at 14^ inches, and during the forward stroke at 
12 inches. A similar inequality is observable in the 
points of release for the front and back strokes. It is 
not, however, a matter of very great practical import- 
ance with stationary engines which run at compara- 



46 



Catechism of the Locomotive. 



tively slow speeds ; but if it is thought desirable, the 
period of admission and the point of release for both 
strokes can be equalized, either by giving the valve 
more lead or lap at one end than the other, or by 
making the one steam-port wider than the other. The 
mechanism employed for moving locomotive slide- 
valves, however, furnishes us with the means of modi- 
fying their motion in relation to that of the piston, 
and of thus equalizing the periods of admission and 
release for the front and back strokes. The methods 
of doing this will be more fully explained hereafter. 



PART V. 
THE EXPANSION OF STEAM. 

Question 55. How can we determine by experiment 
the pressure of the steam in the cylinder at all points oj 
the stroke ? 

Answer. By the use of an instrument made for that 
purpose, called an indicator. Its action can be best ex- 
plained by supposing that we have a small cylinder and 
piston, T, fig. 30, (shown on an enlarged scale in fig. 31) 




Scale | in. = 1 foot. 



attached by a pipe £7 to one end of the cylinder A, so 
that when steam is admitted to the latter it will be 
conducted to the small cylinder T through the pipe U. 
Over the small piston and attached to it is a spiral 
spring, 5 s, fig. 31, which is compressed when the pis- 
ton rises and extended when it falls. To the top of 
the piston-rod, V, a pencil, W, is attached. Behind 
this pencil we will suppose there is a card, abed, 
and that this card is so arranged that we can slide 



48 



Catechism of the Locomotive. 




Scale | in. = 1 inch. 



it horizontally and in contact with the pencil point. 
With only the pressure of the atmosphere above, and 
below the piston T, the spring would be neither com- 
pressed nor extended, and the piston would then stand 
in the position shown. in fig. 31. If now we move the 
the card horizontally, the pencil will draw a line, g, h, 
called the atmospheric line. We will now suppose that 
the' tension of the spring is such that a pressure of 10 
lbs. per square inch above or below the piston will 
either extend or compress the spring J inch. In 
other words, every pound of pressure per square inch 
in the piston will move it 1-40 of an inch. If we 
could produce a vacuum under the piston, it would be 
pressed down by the atmosphere above it 15-40, or § 
of an inch. If, when it is thus depressed, we again 
slide the card along in contact with the pencil-point, 
it will draw another line, e, f, called the vacuum-line. 
Assuming that we have drawn these two lines, and 
that the piston and card are in the position shown in 
figs. 30 and 31, we will then suppose that a recipro- 



The Expansion of /Steam. 49 

eating motion can be given to the card by the lever 
L, M, JV, fig. 30, which is pivoted at M and attached 
at N tc the piston-rod by a short connecting-rod. It 
is obvious that by connecting the upper end L of the 
lever with a rod, L c, to the card, the latter will be 
moved backwards and forwards by the motion of the 
piston B, and that the motion of the card will 
be simultaneous with that of the piston B, but 
of course of shorter stroke. We will assume that 
the stroke of the card is equal to the length of the 
atmospheric and vacuum lines g h and ef, fig. 31. If 
now, the piston being at the beginning of the stroke 
as shown in fig. 30, we admit steam of 85 lbs. effec- 
tive pressure per square inch (which is equal to 
100 lbs. absolute pressure) into the cylinder A, it will 
be conveyed through the pipe U to the cylinder 
T, and will force up the piston 85-40 or 2J inches 
above the atmospheric line, or 100-40 or 2 J inches 
above the vacuum line, as shown in fig. 32, and the 
pencil will draw a vertical line, g i, on the card, (rep- 
resented by a dotted line in fig. 32.) We will sup- 
pose that steam is admitted during 8 inches of the 
stroke, and is then cut off. When the piston B, fig. 
30, has moved that distance, which is one-third of its 
stroke, the card will also have moved one-third of its 
stroke, and will stand in relation to the pencil in the 
position represented in fig. 33, and as the absolute 
steam pressure in the cylinder was maintained at 100 
lbs. while the card was moving that distance, the pen- 
cil will have drawn a horizontal line, ij. The steam 
is now cut off and begins to expand, and its pressure 
is thereby reduced. When the piston of the engine is 
at half-stroke, the card will also be at half-stroke, and 




Scale i in. 



The Expansion of Steams 51 

the steam will be expanded from 8 to 12 inches of ths 
stroke. By the rule given in the answer to question 
20, its absolute pressure would then be 66f lbs., and 
the indicator-piston will then be pressed down by the 
spring, so that the pencil will stand in the position 
shown in fig. 34, or 66f fortieths of an inch above the 
atmospheric line. The pencil meanwhile will have 
drawn the curved line j k. When the piston has 
moved 16 inches, the steam will be expanded to double 
its volume and its absolute pressure will therefore be 
50 lbs., and consequently the pencil will stand 50 for- 
tieths or 1£ inch above the atmospheric line as shown 
in fig. 35, and the pencil will have continued the curve 
j k to /. At 20 inches the steam will have 40 lbs., 
and at the completion of the stroke 33f lbs. absolute 
pressure, and the pencil will have completed the curve 
j kl m n, as shown in figs. 36 and 37. This curve 
is called the expansion curve, and its form is that which 
mathematicians call a hyperbolic curve. If the steam 
is exhausted, the indicator-piston will descend and 
carry the pencil down to the atmospheric line, and the 
vertical line n h, fig. 38, will be drawn. On the re- 
turn stroke, after the steam is exhausted from the 
main cylinder A, fig. 30, the pencil would draw the 
atmospheric line g h, fig. 38, thus showing that there 
is no steam pressure under the piston. Such a dia- 
gram is called an indicator diagram.* In practice 
there are a great many influences which modify it, 
such as condensation, performance of work, imperfec- 



* The indicator used in practice, to show the action of the steam in 
the cylinders of steam engines, differs essentially in its construction from 
that which we have described. The principles of operation are, how- 
ever, the same in both. We will explain the construction of the Rich- 
ard's indicator, the one which is now most generally used, hereafter. 



52 Catechism of the Locomotive. 

tion of valve gear, etc., but for the present these are 
disregarded. 

Question 56. How can we ascertain the pressure of 
the steam for any point of the stroke from such a dia- 
gram? 

Answer. By measuring the vertical distance by the 
expansion curve (fig. 38) from the vacuum or the at- 
mospheric line, as for example 8 j, 12 k, 16 7, 20 m. 
As the indicator spring is extended or compressed one- 
fortieth of au inch* from every pound of pressure per 
square inch, either above or below the indicator pis- 
ton, if we construct a scale S, S, fig. 38, with division 
of one-fortieth of an inch each, one of them will rep- 
resent one pound of pressure per square inch if meas- 
ured vertically from the atmospheric or vacuum line. 
If we sub-divide the vacuum line with the same num- 
ber of parts as there are inches in the stroke of the 
piston (see fig. 39) we can draw vertical lines from 
these points and thus determine the pressure by com- 
paring the length of such lines with the scale S, S. 
Thus the line 8 j measures 100 fortieths of an inch, 
thus showing that the absolute steam pressure at 8 
inches of the stroke was 100 lbs. per square inch ; the 
line 12 k measures 66f fortieths of an inch, thus show- 
ing that at 12 inches of the stroke the steam pressure 
was 66f lbs. At 16, 20 and 24 inches of the stroke 
the vertical lines measure 50, 40 and 33f fortieths ; 
and therefore there were that number of pounds of 
steam pressure when the piston was at the point of the 
stroke named. Similar measurements could be made 
from other points, such as 2, 6, 10, or any other num- 



tion to 



Indicator springs are used of various degrees of tension, in propor- 
i to the steam pressure to be indicated. 



The Expansion of Steam. 



53 



ber of inches of the stroke. Of course, if we measure 
from the vacuum line we will have the absolute steam 
pressure, or the pressure above a vacuum, as it is some- 
times called ; if we measure from the atmospheric line 
we will have the effective pressure, or the pressure 
above the atmosphere. 

Question 57. Bow can we determine the average 
pressure during the whole stroke of steam which works ex- 
pansively ? 

Answer. This can he determined approximately by 
the following method: In the first place, divide the 
vacuum line (fig. 39) into any number of equal divi- 
sions, say six. From the points of division, 4, 8, 12, 




l Z 4 6 3 10 1.2 14 16 18 20 22 Zi 



Scale | in. = 1 inch. 

16 and 20, which in this case correspond with the 
points which represent inches of the stroke, draw per- 
pendicular lines, which will divide the indicator dia- 
gram into six divisions. It is obvious that during the 
time the steam is working full stroke the pressure is 
uniformly 100 lbs. absolute. While the piston is mov- 
ing from 8 to 12 inches the pressure falls from 100 to 
66f lbs., so tbat at 10 inches we have very nearly the 
average pressure during the period named. So from 
12 to 16, 16 to 20 and 20 to 24 the average is nearly 
57.1, 44.4 and 36.3 lbs., respectively. Now, by add- 
ing TOGETHER THE PRESSURES IN THE MIDDLE OF 
EACH ONE OP A NUMBER OF EQUAL DIVISIONS OF 

5*. 



54 Catechism of the Locomotive. 

THE STROKE AND. DIVIDING BY THE NUMBER OF 
DIVISIONS, WE WILL OBTAIN APPROXIMATELY THE 
AVERAGE ABSOLUTE PRESSURE DURING THE WHOLE 
STROKE. TO GET THE AVERAGE EFFECTIVE PRES- 
SURE, DEDUCT THE ATMOSPHERIC PRESSURE FROM 

the result. The calculation would in the above 
case be as follows : 

100 lbs. 
100 " 

80 " 

57.1 

44.4 

36.3 



6)417.8 



69.6=Average absolute pressure. 
15 



54.6=Average effective pressure. 

A more accurate way of calculating the average or 
mean pressure, as it is called, when steam is used ex- 
pansively, and the one which is usually employed, is to 

DIVIDE THE LENGTH OF THE PISTON'S STROKE IN 
INCHES BY THE NUMBER OF INCHES AT WHICH THE 
STEAM IS CUT OFF : THE QUOTIENT IS THE RATIO 
OF EXPANSION. GET THE HYPERBOLIC LOGARITHM 
OF THE RATIO OF EXPANSION FROM THE TABLE OF 
LOGARITHMS IN THE APPENDIX, ADD 1 TO IT, AND 
DIVIDE THE SUM BY THE RATIO OF EXPANSION AND 
MULTIPLY THE QUOTIENT BY THE MEAN ABSOLUTE 
STEAM PRESSURE IN THE CYLINDER DURING ITS AD- 
MISSION. The result will be the mean abso- 
lute PRESSURE DURING THE STROKE. To GET THE 



The Expansion of Steam, 55 

MEAN EFFECTIVE PRESSURE, DEDUCT THE ATMOS- 
PHERIC PRESSURE. 

The calculation for the above example would be 

as follows : 

24 
— — =3=Ratio of expansion. 
8 

1.0986+1 x ioo=69.95=Mean absolute pressure, 
o 
69.95 — 15=54.95= Mean effective pressure. 

The table of hyperbolic logarithms given in the 
appendix will be needed in calculating the mean pres- 
sure of steam used expansively : 

Question 58. What advantages result from using 
steam expansively? 

Answer. There is a very important saving in the 
amount of steam required to do a given amount of 
work, and the strains and shocks which are produced 
by the rapid motion of the piston and other recipro- 
cating and revolving parts of the engine are very 
much diminished by allowing the steam to expand, 
and thus become reduced in pressure during the latter 
part of the stroke. 

Question 59. How is steam saved by using it expan- 
sively f 

Answer. Less steam is required when it is used ex- 
pansively : 

1. Because when steam of a high pressure is intro- 
duced into the cylinder, and allowed to expand until 
its pressure is comparatively low, it escapes at a 
lower pressure than the average pressure during the 
whole stroke. If steam of a pressure equal to the 
average pressure is worked full stroke, it would exert 
exactly the same force on the piston as the steam of 



56 Catechism of the Locomotive. 

higher pressure did when working expansively, but 
the pressure in the latter case, when the piston reaches 
the end of the stroke, or the final pressure, as it is 
called, would be considerably lower than in the other. 
The pressure of steam represents energy, or capacity for 
doing work, and therefore if we allow it to escape with 
a comparatively high pressure without doing work, it 
is a waste of energy. To illustrate this, we will take 
the same conditions which were used in the answer to 
Question 60, in calculating the average pressure. In 
that case the mean absolute pressure of the steam was 
69.95 pounds per square inch, but the pressure at the 
end of the stroke, when the steam escaped, was only 33 f 
pounds absolute. If, therefore, steam had been used 
of the average pressure through the whole stroke, it 
would have escaped with a pressure of 69.95 pounds, 
or more than twice that of the expanded steam, and 
the work done in both cases would have been the 
same. 

2. There is also another incidental advantage in 
this, because low-pressure steam can be exhausted 
more quickly from a cylinder than steam of a high 
pressure, and consequently there is less resistance, or 
back pressure, as it is called, in the exhausted end of 
the cylinder to the movement of the piston. 

3. The causes which produce the greatest economy 
when steam is used expansively cannot be fully ex- 
plained without discussing principles of science more 
abstruse than it is desirable to introduce here. They 
can, however, with the aid of the table of the " Prop- 
erties of Steam,"* in the appendix, be illustrated by a 



*Tlii8 table is copied from Colburn's Treatise on the Locomotive 
Engine. 



The Expansion of Steam, 57 

few simple calculations, so that the economy of using 
steam expansively will be apparent. 

For the basis of the calculations the same data and 
dimensions will be employed that were used in the 
previous illustration ; that is, a cylinder of 16 in. di- 
ameter and piston with 24 in. stroke and steam of 
100 lbs. absolute pressure cut off at 8 in. of the stroke. 
We will suppose, further, that the steam used is gen- 
erated from water of a temperature of 60 degrees, and 
we will then calculate the total number of units of heat 
in the steam used for each stroke of the piston. The 
area of a piston 16 in. in diameter is 201 square 
inches ; and as the steam is admitted until the piston 
moves 8 inches of its stroke, therefore the quantity of 
steam would be 8 times 201 cubic inches, or 

201x8=1608 cubic in. =^2? cubic ft. 

1728 

From the table it will be seen that one cubic foot of 
steam of 100 lbs. pressure weighs .2307 lbs. ; there- 
fore the weight of the fraction of a cubic foot given 
above would be calculated as follows : 

~ 3 °1728~ 08= ' 2146 lb - =wei £ nt of 1608 cubic in - of 
steam of 100 lbs. absolute pressure. 

From the table it will be seen that the total heat 
above zero of steam of 100 lbs. absolute pressure is 
1213.4 degrees. That is, as was explained in answer 
to Question 40,* in order to boil water under a press- 
ure of 100 lbs. per square inch we must first heat 
water up to 327.9 degrees, and then, to convert it into 



* In the illustration used in answer to Question 40, steam of 100 lbs. 
effective pressure was used, whereas in the above oase it is absolute 
pressure. 



58 Catechism of the Locomotive. 

steam, 885.5 degrees more must be added. It was 
also explained in the answer to Question 35 that one 
pound of water heated one degree is the standard of 
measurement or unit of heat Now if we have 1 lb. of 
water with a temperature of zero, evidently it will 
take 1213.4 units of heat to convert it into steam of 
100 lbs. absolute pressure. But as the water from 
which our steam was generated had a temperature of 
60 degrees, we must deduct that much from 1213.4 : 
1213.4 — 60.=1153.4=units of heat in one pound of 
steam of 100 lbs. absolute pressure generated from 
water of 60 degrees temperature. 

If now one pound of steam has 1153.4 units of heat, 
the following calculation will give the units of heat in 
.2146 lbs.: 1153.4 x .2146=247.51=units of heat in 
.2146 lbs., or 1608 cubic in. of steam of 100 lbs. abso- 
lute pressure. 

It was shown in answer to Question 56 that the 
average pressure of steam of 100 lbs. cut off at 8 
in. of the stroke was 69.95 lbs. per square inch. Dis- 
regarding the small fraction, we will call it 70 lbs. 
Now if we admit steam of this pressure through the 
whole stroke of the piston, we will use 4,824 cubic inches. 
It will be found by a calculation similar to the above, 
that to generate this quantity of steam of 70 lbs. 
pressure from water of a temperature of 60 degrees 
would require 527 units of heat, or more than twice as 
many as were required to do the same work with steam 
of 100 lbs. pressure cut off at 8 inches when using 
it expansively during the rest of the stroke. The ac- 
tual difference in practice is not so great as this, be- 
cause the loss of heat from radiation and condensation 
in the cylinder and other causes is greater when steam 



The Expansion of Steam* 59 

of a high pressure is expanded than when lower 
pressure steam is admitted through the whole stroke 
But after allowance is made for all such sources of 
loss and waste, there is still an enormous gain from 
using steam expansively. 

Question 60. What is meant by wire-drawn steam f 

Answer. It is the fall which the pressure of the 
steam undergoes during its passage from the hoiler to 
the cylinder,* and which is due to the contracted 
opening of the steam pipes or valves. 

Question 61. What is the economical effect of re- 
ducing the pressure, or of wire -drawing it, by partly 
closing the valve by which it is admitted to the cylinders. 

Answer. By reducing the pressure of steam in this 
or any other way, it is necessary in doing the same 
amount of work to admit steam to the cylinder for a 
longer period, and therefore to reduce the degree of 
expansion. To illustrate the effect of this, we will 
estimate the total h at required to exert a pressure of 
70 lbs. on the piston described above. It will be as- 
sumed that the steam pressure in the boiler is 100 lbs. 
absolute, and that this is wire-drawn down to 70 lbs. 
and admitted to the cylinder through the whole stroke. 
As was shown in the preceding answer, 4,824 cubic 
inches of steam are required to fill the cylinder. Now 
3,376.8 cubic inches of steam of 100 lbs. pressure, if 
expanded to 70 lbs. pressure, will make 4,824 cubic 
inches. The total heat required to generate 3,376. 8 
cubic inches of steam of 100 lbs. absolute pressure 
from water of 60 degrees is 519.9 units, so that to do 
the same work by using steam of high pressure cut off 
at one-third of the stroke, using steam of low boiler 

* Bankine. 



60 



Catechism of the Locomotive, 



pressure full stroke, and using wire-drawn steam full 
stroke, would, in the example we have selected, require 
247.5, 527 and 519.9 units of heat respectively. 

Question 62. To what extent can we work steam ex- 
pansively, with advantage and economy ? 

Answer. The theoretical economy of using steam in- 
creases with the degree of expansion and the pressure. 
This is shown very clearly in the following table, in 
the first column of which the number of inches of the 
piston stroke is given during which steam is admitted 
to a cylinder 16 in. in diameter and 24 in. stroke. In 
the second column is given the pressure of the steam, 
or initial pressure, as it is called, which must be ad- 
mitted into the cylinder in order to produce a mean 
pressure of 70 lbs. per square inch when it is cut off 
at the point indicated in the first column. In the 
third column is given the total heat which is required 
to generate the steam required in each case, and in 
the last column the percentage of saving is given 
which results from the different degrees of expansion 
and a mean pressure of 70 lbs. per square inch in each 
case. 

RESULTS OF USING STEAM EXPANSIVELY. 



Period of admission or point of cut-off. 



Full stroke 

18 in. == Three-quarters of the stroke, 
12 in. = One-half " " 

8 m. = One-third " " 

6 in. = One-quarter " " 

4 in. = One-sixth " " 

3 in = One-eighth <; " 

2 in. = One-twelfth " " 



Initial press- 


Total heat of 


ure of steam 


steam used. 


in pounds 


in units. 


per 6quare 
inch. 




70. 


527. 


72.5 


408.7 


82.7 


309.5 


100. 


247.5 


117.4 


215.9 


150 5 


186.5 


181.8 


165.8 


241.4 


144.8 



Percentage 
of saving 
compared 
with full 
stroke. 



ooj 
72| 



From this table it; will be seen that theoretically 
22£ per cent, of heat is saved by cutting off at f of 



The Expansion of Steam. 61 

the stroke and using steam of 72.5 lbs. pressure in- 
stead of steam of 70 lbs. worked full stroke. Cutting 
off at half stroke and using steam of 82.7 lbs., 41 J per 
cent, of heat is saved, and cutting off at quarter 
stroke with steam of 117.4 lbs. saves 58 per cent, of 
heat; and at one-twelfth of the stroke, or expanding 
steam of 241.4 lbs. pressure to twelve times its volume, 
saves 72J per cent, of heat. 

As stated before, the above is the theoretical advan- 
tage of using steam expansively. There are, however, 
practical difficulties in the way of using some of these 
high degrees of expansion. It has already been ex- 
plained that if steam is cut off early in the stroke and 
the degree of expansion increased, the pressure and 
consequently the temperature of the steam must also 
be increased. The danger of explosion is greater with 
the higher pressures, and stronger and more expensive 
boilers and machinery are therefore needed. With 
steam of very high temperature the metal of the cyl- 
inders, pistons and valves becomes so much heated 
that they soften, and then the friction of the one on 
the other causes them to cut or scratch each other. 
The high temperature at the same time destroys the 
oil or other lubricant used in contact with the steam. 
It is also impossible to admit and cut off steam very 
early in the stroke with the ordinary mechanical ap- 
pliances used for moving slide-valves of locomotives. 
This latter difficulty will be more fully explained here- 
after. 

6 



PART VI. 

GENERAL DESCRIPTION OF A LOCOMOTIVE 
ENGINE. 

Question 63. What are the principal parts of an or- 
dinary locomotive engine ? 

Answer, A boiler for generating steam and a pair of 
high-pressure steam engines, which are all mounted 
on a suitable frame and wheels adapted for running 
on a track consisting of two iron or steel rails. 

Question 64. Now is the power of high-pressure en- 
gines applied to locomotives ? 

Answer. By connecting the engines with the wheels 
so as to give the latter a rotary motion. 

Question 65. When they revolve what will occur ? 

Answer. Either they will slip on the track, or the 
locomotive will move either backward or forward, ac- 
cording to the direction the wheels are turning. 

Question 66. What will determine whether the wheels 
will slip or the locomotive move f 

Answer. The friction or adhesion, as it is called, be- 
tween the wheels and the track. If this adhesion is 
greater than the resistance opposed to the movement 
of the locomotive, the latter will overcome the resist- 
ance ; but if the latter is greater than the friction, 
the wheels will slip. 

Question 67. Upon what does the amount of fric- 
ion or adhesion of the wheels depend * 



General Description. 6£ 

Answer. Chiefly on the weight which they bear, 
but to some extent upon the condition of the rails. 
Under ordinary circumstances, the adhesion of the 
wheels of a locomotive is in direct proportion to the 
weight they carry. 

Question 68. Why are two cylinders employed on lo- 
comotives ? 

Answer. Because if only one was used, it would be 
impossible or very difficult to start the engine, if it 
should stop on one of the dead points. 

Question 69. How is this difficulty overcome by the 
use of two cylindei s f 

Answer. By attaching the two cranks to the same 
shaft or axle, and placing them at right angles to each 
other, so that when the one is at a dead point the 
other is in the position where the steam can exert the 
maximum power on the crank. 

Question 70. How are the cranks of an ordinary lo- 
comotive made ? 

Answer. They are cast in one piece with the wheels 
that drive the locomotive, which are therefore called 
driving-wheels. In this country the centre portion of 
such wheels, or wheel-centres as they are called, is al- 
ways made of cast iron, with tires of wrought iron or 
steel around the outside, and is fastened to the axles 
of the locomotive. The shaft of a locomotive engine 
is called the main driving-axle, and the wheels attached 
to it the main driving-wheels. 

Question 71. How are the cylinders and driving- 
wheels of a locomotive usually placed? 

Answer. The cylinders A, plates I, II and III, are 
placed at the front end of the locomotive, and the 
main driving-axle, B, far enough behind them to per- 



Catechism of the LoeomMive. 



mit the connecting rods, G, to be attached to pins, D, 
in the cranks, called crank-pins. In this country 
these cranks are now universally placed on the outside 
of the wheels, and therefore the cylinders must be 
placed far enough apart (as shown in fig. 40 and Plate 
III) to permit the connecting-rods to be attached to the 




Fig. 40. 

Scale i in. = l foot. 

crank-pins. The cylinders are therefore placed out- 
side the frames, H, H, Plate III, (the latter are inside 



General Description. 



65 



of the wheels,) and are now nearly always horizontal, 
although in old engines they are often inclined. Plate 
I is a side view of an ordinary eight-wheeled Amer- 
ican locomotive, Plate II a longitudinal section, Plate 
III a plan, and fig. 40, a transverse section through 
the cylinder and smoke-box. 

Question 72. What are the smaller wheels, E E, 
called, and what are they for ? 

Answer. They are called truck-wheels and carry the 
weight of the cylinders and other parts of the front 
end of the locomotive, and serve to guide and steady 
the machine in a manner which will be more fully ex- 
plained hereafter. 

Question 73. Why are more than one pair of driving 
wheels necessary for locomotives ? 

Answer. Because if all the weight which is needed 
to create the requisite adhesion of the wheels of loco- 
motives to pull heavy loads was placed on one pair of 
wheels, it would be so excessive as to partly crush and 
injure the rails. It is therefore distributed, usually 
on two pairs, but sometimes on three or four or even 
more pairs. 

Question 74. Where is the second pair of driving- 
wheels usually placed f 

Answer. These wheels, F — called the back ox trailing 
driving-wheels — are, in the ordinary type of locomo- 
tives used in this country, situated behind the main 
driving-wheels, far enough back to give the room 
necessary for the boiler, G, between the two axles, as 
shown in plates I, II and III. 

Question 75. How are the axles, cylinders, etc., held 
in the right position in relation to each other ? 

Answer. By longitudinal frames, H, H, H, H, which 
6* 



Q6 Catechism of the Locomotive. 

hold the axles in the proper position, and are bolted to 
the cylinders, and also fastened to the boiler at 1, J, 
Plate I. 

Question 76. How is a locomotive engine made to 
run either backward or forward f 

Answer. By having two eccentrics, J, J, Plate III 
(also shown in Plate II,) for each cylinder. One of 
these is fixed or set on the shaft in such a position as 
to move the valve so that the engine will run in one 
direction ; the other eccentric is set so that the engine 
will run the reverse way. The ends of the two eccen- 
tric rods are attached to what is called a link, L, (Plates 
II and III,) the object of which is to furnish the 
means of quickly engaging and disengaging either ec- 
centric rod to or from the rocker, K. The link is 
operated by a system of levers, consisting of the lifting 
shaft, M, and arms, N, N, and the reverse lever, 0, 0, 
(Plate II). The principles and working of these will 
be more fully explained hereafter. 

Question 77. What are the principal parts or "or- 
gans" of a locomotive boiler ? 

Answer. 1. A fire-place, or, as it is called a fi re-box, 
G, (Plate II,) which is surrounded with water. 

2. A cylindrical part, P P, (Plates I and II,) at- 
tached to the fire-box at one end and to a chamber, Q, 
called the smoke-box, at the other 

3. The tubes or flues a a', (Plate II and fig. 40,) 
which connect the fire-box with the smoke-box and 
pass through the cylindrical part of the boiler and are 
surrounded with water. 

4. The smoke-stack or chimney R R. 
Question 78. What is each of these parts or organs 

for, and of what do they consist? 



General Description. 67 

Answer. The fire-box G furnishes the room for 
burning the fuel, and consists of an inner and oater 
shell made of boiler plate, with the space between 
the two filled with water ; a grate, b b, (Plate II,) 
formed of cast-iron bars, with spaces between them 
for admitting air for the combustion of the fuel, 
which is placed on the top of them ; a door, G, called 
the furnace-door, for supplying the grate with fuel ; a 
receptacle, d d, below the grate, to collect ashes, and 
therefore called the ash-pan, which is supplied with 
suitable dampers, n', n', for admitting or excluding the 
air from the fire. 

The cylindrical part P P, or waist of the boiler as 
it is sometimes called, contains the greater part of the 
water to be heated. 

The flues or tubes, as they are generally called, of 
which a locomotive has from one to two hundred, are 
usually two inches in diameter, and about eleven feet 
long. They conduct the smoke and products of com- 
bustion from the fire-box to the smoke-box. These 
tubes are made of small diameter so as to sub-divide 
the smoke into many small streams and thus expose 
it to a large radiating surface through which the heat 
is conducted to the water. 

The smoke-stack serves partly for removing into the 
open air the smoke which passes through the flues, and 
partly for producing a strong draft of air, which is 
indispensably necessary for the rapid combustion of 
the fuel, and also for collecting and extinguishing 
the sparks from the fire. 

Question 79. How is the draft produced in locomotive 
boilers ? 

Answer. By conducting the exhaust steam through 



68 Catechism of the Locomotive. 

pipes (e, e, fig. 40) from the cylinders to the smoke- 
hox and allowing it to escape up the smoke-stack from 
apertures, f J, (Plate II, fig. 40.) called exhaust nozzles. 
The strong current of steam thus produced in the 
smoke-stack produces a vacuum, by which the smoke 
is sucked into the smoke-box with great power and 
forced out of the smoke-stack into the open air. 

Question 80. Bow are the water and fuel carried 
which must be supplied to a locomotive while it is run- 
ning f 

Answer. The water is carried in a tank, which is 
constructed in the form of the letter U, so as to give 
room for the stowage of fuel between its two branches 
or sides. This tank is carried on a set of wheels, and 
forms a separate vehicle, independent of the locomo- 
tive, called a tender, the construction of which will be 
explained in a future chapter. 

Question 81. What are the dimensions of the prin- 
cipal parts of a locomotive ? 

Answer. There is a great variety in the plan, size 
and capacity of locomotives, but the type which is 
more generally used in this country than any other, 
and which has been selected for the preceding illus- 
trations, and will be described in the succeeding 
chapters of the Catechism, has four driving and four 
truck wheels, and weighs in working condition about 
60,000 lbs. The following are the dimensions of its 
principal parts : The driving-wheels are about 5 feet 
and the truck-wheels from 26 to 30 inches in diame- 
ter. The longitudinal distance between the centres 
of the driving-wheels is usually about 7 feet, and 
between the centres of the truck-wheels 5 ft. 9 in., and 
the total distance from the centre of the back driving- 



General Description. 



69 



wheels to the centre of the front truck-wheels, which 
is called the wheel-base, is 21 ft. 8 in. The weight on 
each driving-wheel is usually about 10,000 lbs., and on 
each truck-wheel about 5,000 lbs.- The cylinders are 
16 in. in diameter and the piston has 24 in. stroke, 
and the connecting-rod is 7 ft. long measured between 
the centres of the pins to which it is attached. The 
centres of the cylinders are about 6 feet apart, meas- 
ured across the track. The fire-box inside is 5 feet 
long and 2 ft. 11 in. wide, and the cylindrical part of 
the boiler is 4 feet in diameter measured on the out- 
side of the smallest portion. The water spaces around 
the fire-box are about 3 inches wide. There are 140 
tubes, which are 2 in. in diameter measured on their 
outside, and 11 ft. long. The inside of the smoke- 
stack is 16 in. in diameter, and it is 14 ft. 3 in. high 
measured from the top of the rails. The tender car- 
ries about 1,800 gallons of water and about 8,000 lbs. 
of coal. When loaded it weighs about 40,000 lbs., 
making the total weight of the engine and tender 
100,000 lbs. 

The following is a list of parts designated by the 
letters of reference on plates I, II, III and fig. 40. 



A, A, Cylinders. 

B, Main driving-axle. 

C C, Main connecting-rods. 
I) D, Main crank-pins. 

E, E, Truck-wheels. 

F, Axle of trailing- wheels. 

0, Fire-box. 

H, H, H, Frames. 

1, /, Frame-clamps. 
J, J, Eccentrics. 
K, K, Rockers. 

L L, Links. 

M, Lifting-shaft. 

2V, N, Lifting arms. 

O O, Reverse-levar. 

P P, Cylinder part of boiler. 

Q, Smoke-box. 

B R, Smoke stack or chimney. 



S, Pilot or cow-catcher. 

T, Head-light. 

U, Bell. 

V, Sand-box. 

TV, Whistle. 

X, Dome. 

Y Y, Cab or house. 

Z, Back or trailing-wheel crank- 
pin. 
.,4' Pump air-chamber. 
B', /?', Main driving-wheels. 
C C (7, Supply- pipe. 
Df Front platform. 
E f Bumper timber. 
F' F', Back driving-wheels. 
G' Coupling-pin. 
H' Friction-plate. 

V Check-valve. 



70 



Catechism of the Locomotive, 



IP K', Foot-board. 

L' Lazy cock. 

M' Mud drum. 

N' N', Driving springs. 

PPump 

R' Drop-door or grate. 

& Steam trauge. 

V T' Feed pipe. 

U' W Forward eccentric rods. 

V Y' Backward " " 
X' Lifting-shaft spring. 

Y' Y' Dampers. 

Z' Pushing-bar. 

a a' Tubes. 

b b, Grate. 

c, Fire-box door. 

d d, Ash pan. 

//, Exhaust-nozzles or blast-pipes. 

g, Safety-valve lever. 

h h. Cross-heads. 

i i, Kunning-board. 

;', Throttle-stem. 

I, Throttle-pipe. 
m m, Dry pipe. 
?i, T-pipe. 

o o, Steam-pipe. 

p, Petticoat pipe. 

q, Smoke-box door. 

r, Piston. 

s, Spark-deflector or cone. 

I I, Wire-netting in stack. 
u u u, Boiler-lagging. 

v v, Truck-spring. 



to w. Sector or quadrant. 

x, Blow-off cock. 

e k, Reversing-rod. 

y, Truck centre-pin. 

s, Throttle-lever. 

af a, Tubes. 

1/ &, Truck frame. 

tf c', Bed-plate. 

d f , Boiler brace. 

e? e', Sand pipe. 

fft Equalizing lever for driving 

wheels. 
g r g\ Guide-bars or rods. 

V W, Receptacle for sparks. 
i' i', Bell rope. 

j'j'i Guide yoke. 
k f , Valve-stem. 

V V, Truck equalizing lever. 
m' m' m', Hand-rail. 

n/, Blow-oft cock in mud drum. 

(/, Spring balance. 

p', Pump plunger. 

q' q\ Foot steps. 

r', Brace to smoke-box and frame. 

s' s', Steam-chests. 

V V //, Crown- bare. 
u/, Head-light lamp. 
v', Main valve. 

w', Blow-off cock handle. 
x>, Bell-crank for throttle-valve. 
y', Piston-rod. 
a', Draw-bar. 



PART VII. 
THE LOCOMOTIVE BOILER. 

Question 82. How does the quantity of steam gener- 
ated in locomotive boilers in a given time compare with that 
generated in the boilers of stationary and marine engines ? 

Answer. Locomotive engine boilers must produce 
much more steam in a given time, in proportion to 
their size, than is required of the boilers of any other 
class of engines, (excepting perhaps those of steam 
fire-engines,) because the space which locomotive boil- 
ers can occupy and also their weight is limited. 

Question 83. How is their steam-generating capacity 
increased above that of marine and stationary boilers ? 

Answer. By creating a very strong draft of air 
through the fire and then passing the smoke and 
heated air through a great many small tubes, which 
are surrounded by water. By this means the smoke 
and hot air are divided into many small streams or 
currents which are exposed to the inside surface of 
the tubes to which and to the surrounding water their 
heat is imparted. 

Question 84. How is the action of the exhaust steam 
in producing a draft in the chimney explained? 

Answer. The exhaust steam escapes from the cylin- 
ders through one or two contracted openings or 
exhaust-nozzles (f Plate II, also shown in fig. 40*), 

* The term blast-orifice is also often used to designate these parts 
of locomotives. 



72 Catechism of the Locomotive. 

which point directly up the centre of the chimney or 
smoke-stack. The exhaust steam escapes from this 
orifice with great velocity, and expands as it rises, so 
that it fills the pipe p and the smoke-stack R R. It 
thus acts somewhat like a plunger or piston forced 
violently up the chimney, and pushes up the air above 
it, and, owing to the friction of the particles of air, 
carries that which surrounds it along up the stack, 
from which it all escapes finally into the open air, 
thus leaving a partial vacuum behind in the smoke- 
box. The external pressure of the atmosphere then 
forces in air through any and every opening in the 
smoke-box, to take the place of that already drawn out 
or exhausted from it. As the only inlet is through 
the tubes, to which the gases of combustion have free 
access from the fire-box, and as the external air can 
only pass through the fire-grate, and through the 
burning fuel, to reach the fire-box, there is a constant 
draft of air through the grate as long as the waste 
steam escapes from the blast-pipe and up the chim- 
ney. It is thus that, within certain limits, the more 
the steam that is required, the more the steam that is 
produced ; for all the steam used in the engine draws 
in the air in its final escape, to excite the fire to gen- 
erate more steam.* Sometimes one blast-orifice is 
used for each cylinder, as shown in plates II and III 
and fig. 40 ; in other cases the exhaust steam from 
each cj^linder escapes through the same orifice. 

Question 85. How much water is it necessary to 
evaporate in order to furnish the steam required to run an 
ordinary train at its usual speed ? 



* Colbum's Locomotive Engineering. 



The Locomotive Boiler. 



73 



Answer. For an ordinary "American " locomotive,* 
weighing 60,000 lbs. and with cylinders of 16 inches 
diameter and 24 inches stroke, from 6,000 to 12,000 
lbs. of water must be evaporated per hour. 

Question 86. How much water will a pound of coal 
evaporate in ordinary practice f 

Answer. The quantity of water which is converted 
into steam by a pound of coal varies very materially 
with the quality of the coal, and the construction and 
condition of the boiler ; but from 6 to 8 lbs. of water 
per pound of coal is about the average performance of 
ordinary locomotives. It is, therefore, necessary to 
burn from 500 to 2,000 lbs. of coal per hour in order to 
generate the quantity of steam required by ordinary 
engines. 

Question 87. How large a grate is needed to burn 
this quantity of coal? 

Answer. The maximum rate of combustion may be 
taken at about 125 lbs. of coal on each square foot of 
grate surface per hour, so that to burn 2,000 lbs. we 
need a grate with about 16 square feet of surface. 

Question 88. How much heating surface is needed 
for a given size of grate f 

Answer. In common practice about 50 square feet of 
heating surface are given for each square foot of grate. 
There are, however, no reasons for the proportions of 
either grate or heating surface which are given, ex- 
cepting that it has been found that' they work well 
in practice. It is, however, quite certain that the 
larger a boiler is, and the greater its heating surface 
in proportion to the steam it must generate, other 

* In speaking of "American " locomotives, we mean locomotives 
like that shown in Plate T, with four driving-wheels and a four-wheeled 
truck, and shall so use the term hereafter. 



74 Catechism of the Locomotive. 

things being equal, the more economical will it be in 
its consumption of fuel, or, in other words, the more 
water will it evaporate per pound of coal. 

Question 89. Why is it necessary to use small tubes 
or fines in order to have the required amount of heating 
surface ? 

Answer. Because there is a great deal more surface 
in a small tube of a given length, in proportion to the 
space it occupies, than in a large one. Thus a tube 
two inches in diameter and eleven feet long has 829 
square inches of surface, and one four inches in diame- 
ter has 1,658 square inches, or just double the quan- 
tity. But the four-inch tube occupies four times as 
much space as the other, as it is twice as high and 
twice as wide. Therefore, in proportion to the space 
it occupies, the tube which is two inches in diameter 
has twice as much surface as the larger one. If we 
compare a two-inch with an eight-inch tube, we will 
find that the former has four times as much surface, 
in proportion to its size, as the eight-inch tube. As 
the size and weight of locomotive boilers are limited, 
it is therefore necessary, in order to get the requisite 
heating surface in the space to which we are confined, 
to use tubes of small diameter. 

Small tubes also have the advantage that they may 
be made of thinner material, and yet have the same 
strength to resist a bursting pressure from within, or a 
collapsing pressure from without, as larger tubes made 
of thicker metal. The advantage of thin tubes is, 
that the heat inside of them is conducted to the water 
outside more rapidly than it would be through thicker 
metal, which is important when combustion is as 
rapid as it is in locomotive boilers. 



The Locomotive Boiler, 75 

The reason tubes of smaller diameter than two 
inches are not ordinarily used is because they are then 
liable to become stopped up with cinders and pieces 
of unconsumed fuel. 

Question 90. How is the jire-box of a locomotive 
constructed f 

Answer. It usually consists of a rectangular box 
(G, figs. 41 and 42) about three feet wide* and, for 
the size of engine we have selected as an example, 
about five or five and a half feet long inside. This 
box is composed of metal plates, either iron, steel or 
copper, which, excepting on the front side, are from 
jB fi to i of an inch thick. This box is called the 
inside shell of the fire-box, and is surrounded by an- 
other shell, A B C D E i^, fig. 42, of either iron or 
steel plates, of about the same thickness as those com- 
posing the inside. This is called the outside shell 
of the fire-box and, as already explained, is so much 
larger than the inside that there is a space, called 
the water-space, from 2^ to 4^ inches wide, on all the 
sides of the fire-box between the inner and outer 
plates. 

The top g, g, of the inside shell, which is called the 
crown-sheet or crown-plate, is flat, whereas the outside 
shell is arched, as shown in fig. 42. To the front plate of 
the inside shell the tubes a a', a a' are attached. For 
this reason its thickness is usually made greater than 
that of the other plates, and is usually from § to £ of 
an inch. The edges of one of the plates at each cor- 
ner of the fire-box, where they are united together, as 
shown in figs. 41 and 42, are bent at right angles, and 

* The width is dependent upon the distance between the rails, or 
gauge of the road, as it is called. The above size is for a 4 feet 8J in. 
gauge. 



76 Catechism of the Locomotive, 

the other is fastened to it with rivets from f to f of 
an inch, in diameter. 

The inside and the outside shells of the fire-box are 
united to each other by a wrought-iron bar or ring 
{A F, figs. 41 and 42) wbich completely surrounds 
the inner shell and closes the water-space between 
the two shells. This bar is bent and welded to the 
proper form to extend around the bottom of the inside 
fire-box, and it is riveted to both shells. The water 
in the water-space is in free communication with the 
rest of the water in the boiler; and thus the flat sides 
of the respective shells of the fire-box are exposed to the 
full pressure of the steam, which tends to burst the 
outside shell and collapse the inside one. These flat 
sides, by themselves, would be unable to resist the 
strain upon them, but as the strain upon the re- 
spective fire-boxes is in opposite directions, and neces- 
sarily equal for equal areas of surface, tie-bolts, n, n, 
n. n. (tigs. 41 and 42.) or, as they are called stay-bolts, 
which are from f to 1 inch in diameter, are screwed 
through the plates at frequent intervals, usually from 
Sj to 4-J in. apart, so as to connect the two fire-boxes 
securelv together, the ends of the stav-bolts being also 
riveted or spread out by hammering so as still further 
to increase their holding power. These bolts, owing 
to the expansion and contraction of the boiler and 
other strains to which they are subjected, very fre- 
quently break, and if they are made of solid bars of 
metal there is no way of discovering with certainty 
whether they are in good condition or not without 
taking the boiler to pieces. They should therefore be 
made of the best quality of wrought iron, brass or 
copper and should also be made tubular, that is they 



78 



Catechism of the Locomotive, 




Fig. 42. 
Scale } in. = 1 foot. 

should have a hole through the centre, so that when 
they break the water will escape at the fracture into 
the hole and the leak will thus indicate the defect and 
danger. The latter is much greater from this cause than 
is usually supposed, and it is not unusual to find on 
taking a boiler to pieces that a large number of the 
stay-bolts are broken. 

Question 91. How can the strain on the flat surface 
of a boiler between the stay-bolts be calculated? 

Answer. By multiplying the area in inches 



The Locomotive Boiler. 



79 



BETWEEN ADJACENT STAY-HOLTS MY THE PRESSURE. 

The reason for this is, that each stay-bolt must sus- 
tain the pressure on a part of the plate to which it is 
attached. Thus in fig. 43 it is plain that the bolt S 




Fig. 43. Scale l\ in.=l foot. 

must sustain the pressure on one-half of that part of 
the plate between it and the bolts v, t, w, u, around it, 
or the pressure on the square a b dc, whose sides are 
equal to the distance (4 inches) between the centres of 
the bolts. With a pressure of 100 pounds per square 
inch, the calculation would therefore be : 4 X 4 xl00= 
1,600 lbs. on each bolt. 

Stay-bolts should never be subjected to a strain of 
more than one-eighth or one-tenth of their breaking 
strength. 

Question 92. How do stay-bolts often fail without 
breaking ? 

Answer. By tearing or stripping the thread of the 
bolt, or that in the plate, but oftener perhaps by the 
stretching of the plates between the holes. With a 
heavy pressure, the tendency of the plates between 
the holes, especially if they are heated very hot, is to 



80 Catechism of the Locomotive. 

" bulge " outward and thus stretch the hole in every 
direction until it is so large that the bolt is drawn out 
without much injury to the screw-thread. 

Question 93. How is the fiat-top or crown-sheet 
strengthened ? 

Answer. It is sometimes strengthened with stay- 
bolts similar to those used for the sides, which pass 
through the inner and outer shells ;* but usually the 
crown-sheet is strengthened by a series of iron bars, 
(/, f, fig. 41 and 42) called crown-hars, placed on edge, 
and of considerable depth, which are firmly fastened 
to it by T-head rivets or bolts. The crown-sheet can 
therefore only be crushed downwards by bending these 
bars, which are of great strength. They usually ex- 
tend crosswise of the length of the fire-box, but are 
sometimes placed lengthwise. These bars bear on the 
fire-box only at each end, as shown in fig. 42, and are 
usually made with a projection, k, k, which rests on 
the edge of the side plates. Iron rings or washers 
from j to ljj inches thick are interposed between the 
plate and the bars at the points where the bolts or 
rivets which secure the rivets pass through. This 
permits the water to circulate under the bars, and pre- 
vents the crown-sheet from being burnt or overheated, 
as it would be if the water were excluded from the 
whole under surface of the crown-bars, f The crown- 
bars are also attached to the outer shell and the dome 
by braces, e, e, I, I. 

The opening c, fig. 41, at the back end is for the 
door through which fuel is supplied to the grate. 



♦This method of staying crown-sheets has been extensively used 
on the Baltimore & Ohio and Reading railroads, and is now very gen- 
erally used in Europe. 

t Colburn's Locomotive Engineering. 



The Locomotive Boiler, 81 

Question 94. How are the grates constructed? 

Answer. They are generally made of cast-iron bars, 
and for burning coal are usually arranged so that the 
fire can be shaken by moving the bars. For burning 
anthracite coal, the grates are sometimes made of 
wrought-iron tubes, through which a current of water 
circulates to prevent them from being overheated. 

Question 95. How are cinders and burning coals 
prevented from falling through the grate upon the road? 

Answer. By attaching a sheet-iron receptacle or ash- 
pan {df d', fig. 41) as it is called, under the grate, 
which it completely encloses from the outside air. 
This then serves two purposes, as it is often important 
when the engine is standing still to prevent any ac- 
cess of air to the fire-box, and therefore the ash-pan 
is made to fit tighly to the fire-box. Suitable doors, 
or dampers as they are called, are placed in front and 
behind, and sometimes on the sides, which can be 
opened or closed to admit or exclude air as may be 
needed. 

Question 96. How are the tubes or flues of a locomo- 
tive arranged ? 

Answer. They are fastened into accurately drilled 
holes in the tube sheet (a, a, figs. 41 and 42) which 
forms the front of the fire-box and in similar holes in 
a plate (a', a', fig. 41,) which forms the front end of 
the cylindrical part of the boiler. They thus connect 
the fire-box with the smoke-box. The tubes are ar- 
ranged so that each tube will have a space of from £ 
to \ of an inch between it and those adjoining. 
The position of the holes for the tubes in relation to 
each other is determined by describing from the centre 
of one tube (o, fig. 44) a circle with a radius, o k, 



82 



Catechism of the Locomotive. 



equal to the sum of the diameter of a tuhe and the 
distance which they are intended to be apart, and then 
subdividing this circle with the radius into six parts, 
k, r, s, I, g and p. Each point of subdivision and also 




The Locomotive Boiler. 



83 



the centre, o, of the circle will be the centre of a tube. 
By drawing them from these centres it will be found 
that the distances a b, c d between adjoining tubes 
will be the same between all of them. By describing 
circles from the centres of the outside tubes and sub- 
dividing the circles as before the position of other tubes 
will be determined around those first laid down. This 
can, of course, be carried out indefinitely. A differ- 
ence in the arrangement of the tubes will be observed 
if, when we subdivide the first circle shown in fig. 44, 
instead of commencing from the intersection of a ver- 
tical line we begin from a horizontal line, h i, as 
shown in fig. 45. In the former case the tubes are 
said to be in vertical rows, and in the latter in horizon- 
tal rows. It is apparent from the figures and as shown 
by the arrows that the water can circulate in ascend- 
ing currents more freely when tubes are arranged in 
vertical rows than when they are arranged horizon- 
tally. 

Question 97. How are the tubes fastened and made 
water-tight in the tube-sheets ? 

Answer. They are inserted into the holes drilled to 
receive them, and the ends are allowed to project about 
Fig. 46. Scale J. 




84 



Catechism of the Locomotive. 



a quarter of an inch beyond the tube-sheets. A ta- 
pered plug, fig. 46, is then driven into the tube, to ex- 
pand it so that it will fit the hole. A tool is used 
called a tube-expander, fig. 47, which is what might be 
called an expanding plug, consisting of a number of 
sections, a, b, c, d, e, f, g, h, held together by a spring 
clasp s, which embraces them, as shown in the en- 
graving. This plug when the sections are drawn to- 
gether is inserted into the mouth of the tube, and the 
tapered plug p p, is then driven into the opening left 
in the center of the cluster of sections, which are thus 
expanded. By this means, the ridge a b c d ex- 
pands the tube at the inner edge of the tube-sheet, 
forming a ridge* or corrugation, as shown at c c, fig. 
48. At the same time the shoulder j k I on the tool 
expands the outer edge of the tube somewhat as is 





Fig. 49. 
iTig. 48. Scale 1. 
shown at ff, fig. 48. By repeating this process, and 
slightly turning the expander each time, the tubes can 
be made perfectly water-tight. There are other forms 
of tube-expanders, but the one described, known as 
Prosser's expander, is more generally used than any 
other. In many cases, after the tubes are expanded 
with the tool described, the outer edge is turned over 
still more with what is cabled a thumb-tool, fig. 49, 
probably from its resemblance in form to a man's 



The Locomotive Boiler. 85 

thumb. By placing the curved shoulder a on the end 
f, fig. 48, of the tube it is turned over, somewhat in 
the form shown in the engraving, by repeated blows of 
a hammer on the end of the tool. Copper ferrules, 
represented by the black shading, a a, are also much 
used now on the outside of locomotive tubes, and it is 
said that with them the joints can be kept tight much 
easier than without. By turning over the outside 
edge of the tube as shown in fig. 48, it not only pro- 
tects the copper ferrule, but, as the tubes must act as 
braces to sustain the pressure of steam in the flat 
tube-sheets, it gives the joints the requisite strength 
for resisting such strains. 

Question 98. How can the strain on the cylindrical 
part of a boiler be calculated*? 

Answer. By multiplying the diameter in 

INCHES BY THE LENGTH IN INCHES AND THE PROD- 
UCT BY THE STEAM-PRESSURE PER SQUARE INCH. 

Thus for a boiler 48 inches in diameter and 10 feet 
long with 100 pounds pressure the calculation would 
be 48 xl20x 100=576,000 lbs. 

Question 99. Why do we multiply the diameter, in-> 
stead of the circumference, by the length, to get the strain 
on the cylindrical part ? 

Answer. The reason for multiplying by the diameter 
instead of by the circumference is because only a por- 
tion of the pressure on the inside surface of the boiler 
exerts a force to burst the shell at any one point. 
Thus, supposing the following diagram, fig. 50, to 
represent a section of a boiler, if we have a force act- 
ing on the shell in the direction of the line a b, at the 
point b, where it is exerted against the shell of the 
boiler, it would be composed of two forces, one acting 



86 



Catechism of the Locomotive. 



in the direction b e, and tending to tear the boiler 
apart on the line c d, and the other acting in the di* 




Fig. 50. 

rection fb, to tear it apart on the line h g. It is so 
with all pressure inside the boiler, excepting that, say 
a h, which acts exactly at right aogles to the line of 
rupture c d, it is all composed of two forces, only one 
of which tends to tear the boiler apart at one point. 
It is therefore only a part of the pressure on the cir- 
cumference which tends to burst the boiler at a given 
place, and that part is equivalent to the pressure on 
a surface whose width is equal to the diameter and 
not the circumference. 

This we know is a little difficult for those to under- 
stand who are not familiar with the principles of what 
is called the "resolution of forces," and we will there- 
fore try to make it clear in another way. 

To do this we will suppose that we have a boiler, 
a b, fig. 51, made in two halves and bolted together 
at a and b by flanges. It is evident that if we brought 



The Locomotive Boiler. 87 

a pressure against the inside of the flanges in the di- 
rection of the darts c and d, such a pressure would 




Kg. 51. 

not have a tendency to tear apart the holts a and b. 
Some distortion of the hoiler might in fact take place, 
if, for example, we put a jack-screw inside and forced 
out the flanges as indicated, without subjecting the 
bolts to a tensile strain. We see therefore that the 
forces acting in the direction c and d have no ten- 
dency to tear apart the holts at a and b, hut it is only 
the forces such as e, f and g, which act at right angles 
to a b, that exert a strain on the flanges. 

That this force is equivalent to a pressure on a sur- 
face with a width equal to the diameter of the boiler 
is apparent if we suppose that we have a hoiler, a b, 
fig. 52, and that each half, c and d, is nearly filled 
with some substance, say wood or cement, which is 
fitted so tight that no steam can get between it and 
the shell of the boiler. It is apparent now that if we 
admit steam into the space f, the force exerted on the 
bolts a and b is that due to the pressure on the surface 



88 



Catechism of the Locomotive. 



of the wood or cement exposed to the steam whose 
width is equal to the diameter of the boiler. It might 




Fig. 52. 

be said though that if this substance were elastic, like 
india-rubber, the effect of the steam would be different. 
If it were elastic, and a pressure on the surfaces f 
caused it to spread in the direction g and h so as to 
oroduce a pressure in those directions, it would, as has 
already been shown, not exert a force on the bolts a 
and h to tear them apart, but have a tendency to rup- 
ture the boiler at right angles to a b. The sides of 
jh.3 boiler must therefore have a strength sufficient to 
resist this force which tends to tear them asunder. If 
the boiler is made of iron f inch thick there would be 
a sectional area of 45 square inches on each side, or a 
total of 90 square inches, to resist this strain, so that 
each square inch must bear 6,400 lbs. of strain. The 
c ^rrectness of this rule can be demonstrated by the 
use" of mathematics, which would be out of place 
here. Its practical truth has however been proved by 
experiment 



The Locomotive Boiler. 



89 



Questi6n 100. How much strain per square inch is 
good boiler plate capable of resisting, and how much is it 
safe to subject it to ? 

Answer. There is great variation in the tensile 
strength * of rolled iron boiler plate, but that of good 
plate will average about 50,000 pounds per square inch, 
if thestrain is applied in the direction of the "grain " 
or the fibres of the iron f , and about ten per cent, less 
if the strain is applied crosswise of the grain. It has, 
however, been found by experiment that when a ten- 
sile strain is applied to a bar of iron or other material, 
it is stretched a certain amount in proportion to the 
length of the bar and to the degree of strain to which 
it is subjected. It is found that if this strain does not 
exceed about one-fifth of that which would break the 
bar, it will recover its original length, or will contract 
after being stretched, when the strain is removed. 
The greatest strain which any material will bear 
without being permanently stretched is called its 
limit of elasticity, and so long as this is not exceeded 
no appreciable permanent elongation or "set" will be 
given to iron by any number of applications of such 
strains or loads. If, however, the limit of elasticity is 
exceeded, the metal will be permanently elongated, 
and this elongation will be increased by repeated ap- 
plications of the strain until finally the bar will break. 
At the same time the character of the metal will be al- 
tered by the repeated application of strains greater 
than its elastic limit, and it will become brittle and less 
able to resist a sudden strain, and will ultimately break 

*A force exerted to pull any material apart is called a tensile strain, 
and if exerted to compress it is called a compressive strain. 

fit should be explained that in the process of manufacturing iron 
by rolling, the iron is stretched out into fibres in the direction in which 
it passes between the rolls. 



90 Catechism of the Locomotive, 

short off. It is therefore unsafe to subject iron, or in 
fact any other material, to strains greater than its 
elastic limit. This limit for iron boiler plates may be 
taken at about one-fifth its breaking, or, as it is called, 
ultimate strength. It should be remembered, how- 
ever, in this connection, that it often happens that the 
steam pressure is not the greatest force the boiler 
must withstand, as sudden or unequal expansion and 
contraction are probably more destructive, to locomo- 
tive boilers especially, than the pressure of the steam. 

Question 101. How are the plates of boilers fastened 
together f 

Answer. With rivets, which are made with a head 
at one end, and are inserted while they are red-hot 
into holes drilled or punched in the edges of the 
plates. After they are in the holes a head is 
formed on the other end, either with blows from hand 
hammers, or by a machine constructed for the pur- 
pose. In these machines the rivet after it is in the 
holes is brought between a fixed and a movable die, the 
head which is made with the rivet being placed against 
the fixed die, and the movable die is then pressed, 
either by steam or hydraulic pressure with great force 
against the other end of the rivet, thus forcing the end 
of the rivet into the form of the die, which is made of 
the proper shape and size for the rivet head. The 
powerful pressure which is thus brought on the rivet 
causes it to be pressed into all parts of the two holes, 
thus completely filling them both ; whereas with hand 
riveting, the holes are not nearly so completely filled, 
as it is impossible with blows of a hammer to subject 
the rivets to so powerful or uniform a pressure as 
the machine brings upon them. 



The Locomotive Boiler. 



91 



Question 102. What is the strength of riveted seams 
compared with that of the solid plate? 

Answer. The strength of a riveted seam depends 
very much upon the arrangement and proportion of 
the rivets, but with the best design and construction, 
the seams are always weaker than the solid plates, as 
it is always necessary to cut away a part of the plate 
for the rivet holes, which weakens the plate in three 
ways : 1. By lessening the amount of material to re- 
sist the strains. 2. By weakening that left between 
the holes. 3. By disturbing the uniformity of the dis- 
tribution of the strains. The first cause of weakness 
is obvious from an inspection of an ordinary seam, 
riveted with a single row of rivets, fig. 53. In this 
we have two plates 1\ inches wide and § thick fas- 
tened with four rivets \\ inches in diameter and 1| 



Fig. S3 




inches from centre to centre. The section of the 



92 Catechism of the Locomotive. 

plate calculated with decimals* would therefore be 
.375x7.5=2.81 square inches. A piece H inch wide 
and § inch thick would be removed to form each 
hole, or a sectional area for the whole plate of .375 X 
£875x4 = 1.03 square inches, so that the section of 
the plate would be reduced through the holes 2.81 — 
1.03=1.78 square inches. In other words, on the dot- 
ted line a b it will have only about 63 per cent, of 
the sectional area of the solid plate. 

The second cause of the reduction of strength is 
owing to the injury sustained by the plates during the 
process of drilling and punching. The knowledge exist- 
ing regarding this subject is not very accurate, although 
numerous experiments have been made to determine the 
exact amount of weakening caused by punching plates. 
It is, however, certain that in many cases the strength 
of the metal left between the holes of boiler plates is 
reduced from 10 to 30 per cent, by the process of 
punching. It Is probable, however, that soft ductile 
metal is injured less than that which is harder and 
more brittle. Some kinds of steel plates are especially 
liable to injury from punching. It is also probable 
that the condition of the punch, and the proportions 
of the die used with it, have much to do with its effect 
upon the metal 

The third caust) of weakness is owing to the fact 
that if one or more holes are made in a plate of any 
material, and it is then subjected to a tensile strain, 
the strain, instead of being equally distributed through 
the section left between the holes, will be greatest in 
that part of the metal nearest them. This can be illus- 



* In the following calculations all the dimensions have for conven- 
ience been reduced to decimals. 



The Locomotive Boiler. 



93 



trated by taking a band of india-rubber, fig. 54, and cut- 
ting a round hole in it to represent a rivet hole. If we 

%. S4 





draw two parallel lines, A B, across the band and then 
stretch it, the lines, instead of remaining parallel 
when the band is stretched, will separate most next 
to the hole, as shown in fig. 55, indicating that the 
fibres of the rubber nearest the hole are strained most. 
A similar effect takes place when a plate of iron is 
stretched, so that a fracture is liable to begin next to 
the hole, after which the plate will be broken as it 
were in detail. 

Question 103. How may a boiler seam like that 
shown in Jig. 53 break? 

Answer. It may break in three different ways : 

1. By the plate tearing between the rivet holes on 
the line a b. 

2. By the rivets shearing off. 

3. By the plate in front of the rivets crushing, as 
shown in fig. 56. 

Question 104. How can the strength of a boiler 
seam be calculated at each of these three 'points t 

Answer. The strength through the rivet holes is 
calculated by taking the area in square inches 

OF THE METAL WHICH IS LEFT BETWEEN THE RIVET 
HOLES, AND MULTIPLYING IT BY THE ULTIMATE 
STRENGTH OF THE METAL AFTER THE HOLES ARE 



94 Catechism of the Locomotive. 

made. Thus, in fig. 53, the area of eacli of the plates 
between the rivet holes is 1.78 square inches. As al- 

Fig.56 




ready stated, good boiler plate will break at a strain 
of about 50,000 pounds in the direction of its fibres,* 
but the strength of the metal left between punched 
holes is probably 20 per cent, and that between 
drilled holes 10 per cent, less than that of the solid 
plate. We must, therefore, in calculating the strength 
of a punched seam, take the ultimate strength of the 
metal between the holes at only 40,000 pounds per 
square inch. The calculation for the strength through 
the holes would therefore be: 1.78x40,000=71,200 
pounds. 

It has also been found by experiment that the 
strength of rivets to resist shearing is about the same 
as that of good boiler plate to resist tearing apart, or 
50,000 lbs. per square inch. The strength of the rivets, 
therefore, is calculated by multiplying the area 

IN SQUARE INCHES OF ONE RIVET BY THE NUMBER 
OF RIVETS, AND THE PRODUCT BY THE STRENGTH 



* Boiler plates should always be so arranged that the greatest strain 
will come on them in the direction of their greatest strength, which is 
parallel with the fibres of the metal, 



The Locomotive Boiler, 95 

OF THE METAL TO RESIST SHEARING. The calcula- 
tion for fig. 53 would therefore be : 

Area of }} rivet=.3712x4x50,000=74,240. 

or a little more than the strength of the plates through 
the holes. 

The resistance offered by a plate to the crushing 
strain of a rivet has been found also by experiment to 
be about 90,000 pounds per square inch. It can be 
proved that the area which resists the crushing strain 
of a rivet in a plate, fig. 53, is measured by multi- 
plying THE DIAMETER OF THE RIVET BY THE 

thickness of the plate. The calculation for the 
strength of this part of the seam will therefore be: di- 
ameter of hole = .6875 x.375x4x 90,000=92,812. 

The strength of the solid plate would be equal to 
its sectional area multiplied by 50,000 pounds, 
or 7.5 X .375x50,000=140,625 pounds. The ultimate 
strength of our seam would then be as follows : 

Plates through rivet holes (tearing) = 71,200 lbs. 

Rivets (shearing) = 72,240 lbs. 

Plates in front of rivets (crushing) = 92,812 lbs. 

Solid plate (tearing) =140,625 lbs 

It will thus be seen that the strength of the weakest 
part of the above seam, fastened with a single row of 
rivets in punched holes, is very little more than half 
(50.6 per cent.) of that of the plates. It will be no- 
ticed that the weakest part of the seam is the plates 
between the holes. 

Question 105. How can the strength of such a single- 
riveted boiler seam be increased ? 

Answer. The most obvious way of increasing the 
strength of such a seam is to place, or, as it is called, 



96 



Catechism of the Locomotive, 



space, the rivets further apart, which would leave more 

metal between the holes, and thus strengthen the seam 

at its weakest part. But if this is done, it is said that 

there is difficulty in keeping the seam water-tight, as 

the plates are then liable to spring apart between me 

rivets. Another way of increasing its strength is to 

drill the rivet holes. As already stated, the difference 

in the strength of the metal left between drilled and 

punched holes has been shown to be from 10 to 20 per 

cent. There is also another advantage in drilling the 

holes for rivets. In punching them, it is necessary to 

punch each plate separately, and even with the utmost 

care and skill it is impossible to get the holes to match 

perfectly. Some of them will overlap each other, as 

Fig. S7 




The Locomotive Boiler. 97 

shown in fig. 57, so that when the rivet is set, it will 
assume somewhat the form shown in fig. 58. There 
is then danger that those rivets which fill the holes that 
match each other will be subjected to an undue strain. 
If, for example, we have five rivet holes, as shown in 
fig. 59, and only the centre ones correspond with each 
other, then the rivets in all the other holes will as- 
sume somewhat the form shown in fig. 58, and there- 
fore the centre rivet c, in fig. 59, which fits the holes 
accurately, must take the strain of the other four until 
they draw up " to a bearing." Under such circum- 
stances, which are not unusual, there will be great 
danger either of shearing off the rivet c, or of starting 
a fracture in the plates, as indicated by the irregular 
line a b, between the adjoining rivets. It is also ob- 
vious that a rivet like the one in fig. 58 will not hold 
the plates together so well as one which fits more per- 
fectly, as shown in section in fig. 53, and therefore 
there is more danger of leakage between the plates 
from badly fitted rivets than from those which fill 
the holes more perfectly ; consequently rivets which 
fit imperfectly must be placed nearer together than 
those which are well fitted. It is true that rivets 
which are set with a riveting machine fill any inaccu- 
racies of the holes more perfectly than those which are 
set by hand. But even if they are made to fill the 
holes as shown in fig. 60 they are still not so strong 

Mg. 60 




to resist shearing nor so efficient in holding the 



98 Catechism of the Locomotive. 

plates together as they would be if the holes conformed 
more perfectly to each other. In drilling the holes, 
the second plate can he drilled from the holes in the 
first, so that the holes in each will correspond with 
each other perfectly. The rivets will therefore fit 
more accurately, and consequently can he spaced fur- 
ther apart, and still keep the plates tight, and thus 
have more material between the holes, which is the 
weakest part of the seam. It has been shown that a 
rivet j| inch in diameter has a resistance to "shear- 
ing of 18,560 pounds. There is therefore no advan- 
tage in spacing such rivets further apart than 1||- 
from centre to centre, because the metal left between 
drilled holes that distance apart would be slightly 
stronger than the rivets. If therefore the rivets are 
placed further apart, their diameter must be increased. 
There is, however, a limit beyond which the diameters 
of rivets cannot be increased with advantage, because 
if we increase their diameters, their sectional area to 
resist shearing is increased in proportion to the square 
of the diameter, whereas the section of metal in the 
plate to resist crushing is increased only in proportion 
to the diameter. This will be apparent if we compare a 
rivet ^ inch with one 1 inch in diameter. The first has 
a section^ area of .1963 inch, the other .7854 inch, or 
four times that of the first one. Now the area which re- 
sists the crushing strain of the rivets is increased only in 
proportion to their diameters, or is twice as much foi 
the one as for the other. If, therefore, we increase 
the diameters of the rivets, we very soon reach a 
point at which the plate has less strength to resist 
crushing than the rivet has to resist shearing. The 
diameter of rivet which will give just the same resist- 



The Locomotive Boiler. 



99 



ance to both strains varies with the thickness of the 
plates ; with § inch plates a -f- rivet will have a resist- 
ance to shearing of 30,065 pounds and the plate in 
front of it a resistance to crushing of 29,530 pounds. 
A 1 rivet is, therefore, the largest size which can be 
used to advantage in § plates. If now we were to 
space such rivets so far apart that the metal left be- 
tween the holes would have a strength just equal to 
that of the rivets, we would have the strongest possi- 
ble seam that can be made with a single row of rivets. 
This distance would be If inches between the edges 
of the rivets, or 2f from center to center, as shown in 



< «%. 




fig. 61. The following table will show the strength of 
such a seam composed of four rivets, and two plates 
10^ inches wide,* with drilled holes : 

Plates through rivet holes (tearing) 118,125 lbs. 

Rivets (shearing) 120,260 lbs. 

Plates in front of rivets (crushing) 118,125 lbs. 

Solid plates (tearing) 196.875 lbs. 

* It has been necessary to take for an illustration, plates of a different 
width from the preceding example, in order to get an even number of 
spaces between the rivets in each case. 



100 Catechism of the Locomotive, 

From this it is seen that the strength of the seam 
with drilled plates is 60 per cent, of that of the solid 
plates, or it is about 18 J per cent, stronger than that 
made with plates having punched holes and the rivets 
nearer together. It should be noted that a great part 
of the superiority of the seams made with drilled holes 
is due to the superior accuracy of the work done in 
that way, which makes it possible to use larger rivets 
spaced further apart. It is probable that with the use 
of some recently designed machines, intended to pro- 
duce greater accuracy in punching rivet holes, part of 
the above advantage may be realized with that kind of 
work. The greatest distance that rivets may be 
spaced apart without incurring danger of leakage be- 
tween the plates must, however, be determined more 
by practical than theoretical considerations. It is cer- 
tain, however, that rivets may be spaced much further 
apart than they are in ordinary practice, and the 
seams still be kept tight, if the work is done with suf- 
ficient accuracy and care. 

Question 106. What other methods are there of 
making boiler seams which are stronger than those which 
have been described ? 

Answer. In this country two rows of rivets are used 
and also what is called a "welt" or covering-strip, 
the latter with both single and double-riveted seams. 

Question 107. How are the rivets arranged when 
two rows are used? 

Answer. They are often placed just behind each 
other as shown in fig. 62, which is called chain-riveting. 
Such an arrangement of rivets obviously adds nothing 
to the strength of the seam, because its weakest part, 
as has already been shown, is the section of the plates 



The Locomotive Boiler. 101 

through the rivet-holes, and this is not at all strength- 
ened by adding another row of rivets, because the 

ly. 62 



plates are just as liable to break through the rivet- 
holes with two rows of rivets as they would be with 
one. 

A much better arrangement is to place them alter- 
nately in the two rows, as shown in fig. 63. Rivets 
arranged in that way are said to be staggered, or placed 
zigzag. The method of laying off the holes and pro- 
portioning such a seam in order to get the most 
strength is, first, to determine the greatest distance 
which can be allowed between the rivet-holes, and yet 
keep the seams water-tight. Supposing this is l-, 5 6 - 
inches, # with plates -f inch thick, the diameter of rivet 
whose sectional area will give an equal amount of 
strength must then be calculated. From the pre- 
ceding data it will be found that for drilled plates the 

* That and even greater distances between the odges of the holes are 
now used successfully with J -inch plates. 

<)* 



102 



Catechism of the Locomotive. 



resistance of the portion left between such holes will 
be 22,148 pounds, and a rivet f inch in diameter will 

Fig. 68. 




have a resistance of 22,085 pounds. On the line a b, 
fig. 63, which is to be the first row of rivets, we will 
draw one hole, c. From the center of this hole we 
will describe the arc of a circle, d e, with a radius, c d, 
equal to the sum of the distance between the holes, 
If inches, and one-half the diameter of the hole, or f 
inch, making the radius If inches. From d, the in- 
tersection of this arc with the line of rivets, a b, with 
the same radius, we will step off the distance dff will 
then be the centre of the second rivet-hole on the line 
a, b. The rivet can therefore be drawn, and from its 
centre, with the same radius employed before, another 
arc, d g, should be drawn. If now we draw a rivet- 
hole (h) between the two arcs and touching each of 
them, we will have all three of the holes so arranged 
that the metal between the holes c,f, will be just 



The Locomotive Boiler. 103 

equal to that between them and the hole h. In other 

words, the strength of the plates on the line c f is 

just the same as on the line c h f. Therefore the 

strength of the plates on the straight line a b is just 

the same as on the zigzag line c h f etc. The 

strength of this seam would therefore be as follows : 

Plates through rivet-holes (tearing) 110,742 lbs. 

Rivets (shearing) 110,425 lbs. 

Plates in front of rivets (crushing) 126,562 lbs. 

Solid plates ( tearing) 158,205 lbs. 

The weakest portion of this seam, it will be seem 
has a strength of 70 per cent, of the plate, or is 38 per 
cent, stronger than a single-riveted seam with punched 
holes. If we were to use -f- inch rivets and make the 
spaces between them If inches, the strength of a sim- 
ilar seam would be as follows : 

Plates through rivet-holes (tearing) 147,656 lbs. 

Rivets (shearing) 1 50,325 lbs. 

Plates in front of rivets (crushing) 147,656 lbs. 

Solid plates (tearing) 205,078 lbs. 

This seam would then have a strength of 72 
per cent, of the solid plates, or be 42J per cent, 
stronger than the ordinary riveted seam with punched 
holes. It is important to observe that an increase of 
strength results from the use of larger rivets spaced 
farther apart than is usual in ordinary practice, and 
that this is possible only with the best and most accu- 
rate workmanship. 

Question 108. What is the form of construction oj 
boiler seams made with a welt or covering-strip ? 

Answer. The plates (a, b, fig. 64) are lapped over 
each other as for an ordinary seam. Another plate, c, 
about nine inches wide, is then placed on the inside of 
the seam and bent so as to conform to the lap of the 



104 



Catechism of the Locomotive. 



two plates. The rivets r, whether a double or- single 
row, pass through all three plates, and two more rows 



Fig. 64 




of rivets are put next to the edges of the covering 
plate, c. It is plain that the strength of the seam, r, 
is increased up to a certain point by an amount just 
equal to that of the rivets in the edges of the covering 
plate. If, however, these are placed too close together, 
the plates a and b will be weaker through the outside 
rows of rivets than the seam is through either of the 
outside ones and the middle one taken together. If, 
for example, we take a single-riveted seam, like that 
shown in fig. 53, whose strength is only a little more 
than half that of the solid plate, and should add to it 



The Locomotive Boiler. 105 

a covering plate, as shown in fig. 64, and then space 
the rivets in the edges of the covering plate the 
same distance apart as in the middle seam, then ob- 
viously the plates would be just as liable to break 
through the outer rows of holes as through the center 
row before the covering plate was added. H, however, the 
holes in the two outside plates are spaced at say twice 
the distance apart, or 3f inches, then the only way the 
seam can break through the outer rows of holes is by 
shearing the rivets, because the plates between the 
holes are then stronger than the rivets. But before 
these rivets can be sheared, the centre seam must give 
way. Thus the strength of such a seam is equal to 

THE SUM OF THE STRENGTH AT THE WEAKEST 
POINTS OF THE MIDDLE AND THE OUTSIDE SEAMS. 

The strength of the plates between the holes of the 
outside rows of rivets must, however, be as great as 
the sum referred to, otherwise the seam will be the 
weakest at that point, and the failure will occur there. 
The rivets in the outside rows should be spaced at least 
twice as far apart as those in the middle seam. The 
number of rivets to resist shearing will then be 50 per 
cent, greater, so that the strength of a seam like that 
shown in fig. 53, with a covering plate added, will be 
as follows : 

Plates through outside rows of rivet-holes (tearing) 91,880 lbs. 

Rivets in one outside and middle row (shearing) 111,360 lbs. 

Plates in front of rivets (crushing) 139,218 lbs. 

Solid plates (tearing) 140,625 lbs. 

An ordinary single-riveted seam with punched 
holes, with a welt or covering plate added, would thus 
have a strength equal to 65.3 per cent, of the solid 
plate, or be 29 per cent, stronger than the seam with- 
out the covering plate. It is probable, however, that 



106 Catechism of the Locomotive. 

the injury to the plate from punching the outside rows 
of holes which are further apart is not so great as it is 
when they are punched nearer together and to the 
edge, so that the strength is somewhat greater than 
our estimate. 

The relative strength of the different forms of seams 
described in percentage of the strength of the solid 

plate is then as follows : 

Percentage of 
strength com- 
pared with 
solid plate. 

Single-riveted seam, punched holes -J-£- rivets 50.6 

" " drilled " £ " 60. 

Double-riveted seam, drilled zigzag holes, .f rivets 70. 

" " f " 72. 

Single riveted seam, punched holes with covering plate 65.3 

Question 109. Are there any other forms of boiler 
seams used? 

Answer. In Europe what are called butt-joints are 
used to some extent. In these the ends of the two 
plates abut against each other, with a covering strip 
on one or both sides. This form of joint is, however, 
not used in this country, and therefore its peculiari- 
ties will not be described. 

Question 110. How are the seams of boilers made 
water-tight ? 

Answer. By what is called caulking. That is, by the 
use of a blunt instrument somewhat resembling a 
chisel, the end of which is placed against one or both 
of the edges of the plates c, d, fig. 53, which are then 
riveted down by blows of a hammer, somewhat as the 
joints of a ship are made tight. Before the edges, 
which are called the caulking edges, of the plates are 
made tight in this way, they are cut or trimmed off with 



The Locomotive Boiler 



107 



a chisel. In this process the plate under the edge is 
often injured seriously by the carelessness of work- 
men, who sometimes allow the chisel to cut a groove 
in the plate under the edge, thus weakening it at a 
point where the greatest strength is needed. There 
is also danger of forcing the plates apart in the man- 
ner shown in fig. 65, if it is done carelessly and with 
a heavy hammer. 

Fig. 65 




Question 111. How are the fiat ends of the boiler 
strengthened ? 

Answer. By braces, u, u, r, r, fig. 41, which are fas- 
tened to the end plates and to the outer shell of the 
boiler. They are fastened at one end to j_ shaped 
pieces called crow-feet, which are riveted to the end 
plates of the boiler. At the other end they are made 
with a broad foot, which is riveted to the outer shell 
of the boiler. Especial attention should be given to 
the form, proportion and arrangement of these braces 
when a boiler is constructed, and they should be fre- 
quently examined while the engine is in use, as they 
are liable to be neglected or carelessly constructed and 
to become weakened or broken by corrosion, or 



108 Catechism of the Locomotive. 

the constant strain to which they are subjected. 
Great ignorance is often displayed in the design and 
proportions of these braces, especially in their attach- 
ments to the shell of the boiler. 

Question 112. How should the braces for strengthen- 
ing the ends of a boiler be proportioned ? 

Answer. Every part should be made equally strong. 
If, for example, the brace itself is made of a bar of round 
iron one inch in diameter, its sectional area would be 
.7854 square inch. The iron used for these braces 
should be of such strength that a force of not less than 
50,000 lbs. per square inch of transverse section should 
be required to tear it apart lengthwise. A bar of the 
size referred to would therefore require not less than 
39,270 pounds to pull it apart. All the other parts 
should be capable of resisting an equal strain. It is, 
for example, not unusual to find a brace of the size we 
have described, and even of larger diameter, fastened 
to a crow-foot which is attached to the boiler plate with 
two rivets § inches in diameter. A similar fastening 
for the other end of the brace is also often used. The 
sectional area of these two rivets is considerably less 
than that of the brace, and at the same time the strain 
is brought upon them at such an angle as to have a 
tendency to " snap " them off. For this reason, and 
also because a rivet is apt to be deteriorated in 
strength by the hammering, the rivets should always 
have a sectional area very nearly or quite double that 
of the bar which forms the brace. The metal around 
the eyes through which the pins are inserted should alsc 
be carefully proportioned, and the transverse section a : 
any one point should always be at least 1J times greatei 
than that of the bar. The area of the pins used for 



The Locomotive Boiler, 109 

attaching the bars to the crow-feet should always be a 
little more than half that of the bar. That is, an inch 
bar should have a pin not less than f inch in diame- 
ter. When flat braces are used, it is not unusual to 
find a bar 3 inches wide with a hole an inch in diame- 
ter punched or drilled so near the end that a pin is 
sure either to pull out the end of the bar or else to 
break it crosswise at the hole with a much less strain 
than the brace itself would resist. The ends of braces 
should always be enlarged" enough to give them suffi- 
cient strength to resist as much strain as the bar itself. 
Although these precautions may appear unimportant, 
and unfortunately are often so regarded, yet it is 
upon just such details as these that the lives and the 
safety of every locomotive runner, fireman and others 
near them are constantly dependent. 

Question 113. How much water is usually carriedin 
a locomotive boiler f 

Answer. There must always be enough water in the 
boiler to cover completely all the parts which are ex- 
posed to the fire, otherwise they will be heated to so 
high a temperature as to be very much weakened or 
permanently injured. In order to be sure that all the 
heating-surface will at all times be covered with water, 
it is usually carried so that its surface will be from 4 
to 8 inches above the crown-sheet. 

Question 114. How much space should there be over 
the water for steam ? 

Answer. No exact rule can be given to determine 
this. It may, however, generally be assumed that the 
more steam space the better. In order to increase 
the steam room, locomotive boilers are very generally 
made in this country with what is called a wagon-top, 
10 



110 Catechism of the Locomotive. 

D C, fig, 41, that is, the outside shell of the boiler 
over the fire-box is elevated from 4 to 12 or even 18 
inches above the cylindrical part. 

Question 115. What is a steam-dome and for what 
purpose is it intended ? 

Answer. A steam-dome, X, fig. 41, is a c}4indrical 
chamber made of boiler-plate and attached to the top 
of the boiler. Its object is to increase the steam room 
and to furnish a reservoir which is elevated considera- 
bly above the surface of the water, from which the 
supply of steam to be used in the cylinders can be 
drawn. The reason for drawing the steam from a 
point considerably above the water is that during 
ebullition more or less spray or particles of water are 
thrown up and mixed with the steam. When this is 
the case, steam is said to be wet, and when there is 
little or no unevaporated water mixed with it it is said 
to be dry. It is found by experience that wet steam 
is much less efficient than that which is dry. There is 
also danger that the cylinders, pistons or other parts of 
the machinery may be injured if much water is car- 
ried over from the boiler with the steam, because 
water will be discharged so slowly from the cylinders 
that there is not time for it to escape before the 
piston must complete its stroke, so that the C3 r linder- 
heads will be "knocked out," or the cylinder itself or 
the piston will be broken. The reason for drawing or 
"taking" steam from a point considerably above the 
water is because there is less spray there than there 
is near the surface, and the hottest steam, which is 
also the dryest, ascends to the highest part of the 
steam space. 

Question 116. Where is the dome usually placed f 



The Locomotive Boiler, 111 

Answer. In this country it is usually placed over 
the fire-box, but in Europe it is placed further for- 
ward, either about the centre of the boiler or near the 
front end of the tubes. Sometimes two domes are used 
on engines, in this country, one over the fire-box and 
another near the front end. 

Question 117. How is the steam conducted from the 
dome to the cylinders ? 

Answer. By a pipe / m m, fig. 41, called the dry- 
pipe, which extends from the top of the dome to the 
front tube-plate. On the front side of the tube-plate 
and inside the smoke-box two curved pipes, 0, fig. 41, 
(shown also in fig. 43,) called steam-pipes, are attached 
to the dry -pipe at one end, and to the cylinders at the 
other. The vertical portion of the dry-pipe in the 
dome, sometimes called the throttle-pipe, is usually 
made of cast iron, the horizontal part of wrought iron, 
and the steam pipes of cast iron. 

Question 118. How is the loss of heat from loco- 
motive boilers by radiation and convection prevented % 

Answer. 'By covering the boiler and dome with 
wood, called lagging, about |- inch thick, which is a poor 
conductor of heat, and then covering the outside of the 
wood with Russia iron, the smooth, polished surface of 
which is a poor radiator of heat. 

Question 119. What is the smoke-box for ? 

Answer. The smoke-box Q is simply a convenient 
receptacle for the smoke before it escapes into the 
chimney or smoke-stack, which is attached to the top 
of the smoke-box. It also affords a convenient place 
for the steam and exhaust pipes, where they are sur- 
rounded with hot air and smoke, and not exposed to 
loss of heat by radiation. The front end of the smoke- 



112 Catechism of the Locomotive. 

box is usually made of cast iron, with a large door m 
the centre which affords access to the inside. 

Question 120. How are the chimneys or smokestacks 
of locomotives constructed ? 

Answer. The forms of smoke-stacks which have been 
used are almost numberless. For burning bituminous 
coal and wood they are generally made with a central 
pipe, R, fig. 41, and a conical-shaped cast-iron plate, 
S, called the cone or spark deflector, which, as the latter 
name implies, is intended to deflect the motion of the 
sparks and cinders which are carried up with the as- 
cending current of smoke and air in the pipe R, so as 
to prevent them from escaping into the open air while 
they are incandescent, or " alive." A wire netting, 1 1, 
is also provided, which is intended as a sort of sieve to 
enclose the sparks and cinders, and at the same time 
allow the smoke to escape. The receptacle h h is in- 
tended as a chamber in which the burning cinders 
will be extinguished before they escape. For burning 
anthracite coal, a simple straight pipe, without a de- 
flector or wire netting, is ordinarily used. 

Question 121. What are the proportions and mate- 
rials usually employed in the construction of smoke- 
stacks f 

Answer. The inside pipe R, fig. 41, is usually made 
of the same diameter as the cylinders, or an inch or 
two smaller. For the other dimensions there are no 
established rules, excepting for the height of the top 
of the chimney above the rail, which is usually from 
14 to 15 feet. The outsides of smoke-stacks are made 
of sheet iron, but the upper part is now sometimes 
made of cast iron, so as to withstand the abrasion of 
the sparks and cinders longer than sheet iron wilL 



The Locomotive Boiler. 113 

For very warm and damp climates, the outsides of 
smoke-stacks are sometimes made of copper to resist 
corrosion, which is very destructive to all iron struc- 
tures in those countries. The wire netting is made 
of iron or steel wire from iV to -3V of an inch in 
diameter, and with from 3 to 4 meshes to the inch. 

Question 122. What is the pipe N, Jig. 41, intended 
for? 

Answer. It is intended to conduct the exhaust 
steam and a portion of the smoke from the bottom of 
the smoke-box, where the steam escapes, to the base 
of the smoke-stack. In nearly all European engines, 
the exhaust steam escapes at the top of the smoke- 
box just below the aperture of the smoke-stack. 
There is, however, often difficulty in equalizing the 
draft in the tubes, that is, to get an equal amount of 
smoke to pass through all of them. By the use of the 
pipe P, called the inside pipe or petticoat pipe, it is 
thought that the draft in the tubes can be equalized 
much better, as a part of the smoke is drawn out of 
the smoke-box at the top and part at the bottom of 
the smoke-box. The pipe is usually made in two 
parts, which slide into each other like a telescope. 
The distance of the upper end from the top of the 
smoke-box and that of the lower end from the bottom 
can thus be increased or diminished, and if the draft is 
greater through the upper tubes than through the 
lower ones, or vice versa, it can be regulated or equal- 
ized by simply raising or lowering the top or bottom 
of the petticoat pipe. Sometimes this pipe is made 
with openings and a kind of deflectors over them be- 
tween the two ends. It is then called a flounced petti- 
coat pipe, for obvious reasons. 
10* 



114 Catechism of the Locomotive, 

No exact theory can be stated regarding the pro- 
portions of these pipes, or the results effected by them, 
which can be determined only by practical experience. 
Some more accurate knowledge concerning them is, 
however, much needed. 



PART VIII. 
THE BOILER ATTACHMENTS. 

Question 123. How is water supplied to the boiler to 
replace that which is converted into steam f 

Answer. It is usually forced into the boiler against 
the steam pressure by force pumps, but another in- 
strument called an injector is now much used. 

Question 124. What is the form of construction and 
principle of the operation of such force pumps ? 

Answer. The ordinary single-acting force pump, fig. 
66, used on locomotive and other steam engines 
consists of Si pump barrel, A A, which is a cast-iron or 
brass cylinder in which a tight-fitting piston, B B, 
called the pump-plunger, works. This piston or 
plunger is simply a round rod which works air-tight 
through what is called a stuffing box, G, whose con- 
struction will be fully explained hereafter. The 
plunger receives a reciprocating motion, usually from 
the piston-rod of the engine, but is sometimes worked 
by a small crank attached to one of the crank-pins, or 
by an eccentric on one of the axles. The pump-barrel 
is connected with the water-tank of the tender by the 
suction-pipe, D, and with the water-space of the boiler 
by the feed-pipe, E E. Over the suction-pipe D is a 
valve, F, called the suction-valve, which opens upward, 
and below the feed-pipe, E, is another valve, G, called 
the pressure-valve. These valves are cylindrical and 



116 



Catechism of the Locomotive. 



made of brass, and rest on brass seats, g, g, to which 
they are fitted so as to be water-tight. They work in 
guides, k, k, called cages, the form of which is more 
clearly shown in the section, fig. 67, and the plan, fig. 
68. When the plunger is drawn out of the pump- 
cylinder it creates a vacuum behind it, and the pres- 




sure above the valve G closes it, while the atmospheric 
pressure on the water in the tank forces it into the 
suction-pipe, opens the valve F, and fills the pump- 
cylinder. When the plunger is forced back again the 
force with which it presses against the water in the 
pump-barrel, A, closes the valve F, and opens the 
pressure-valve G, and the water is then forced through 
the feed-pipe into the boiler. In order to be certain 



The Boiler Attachments. 117 

that the water in the boiler will not flow back into the 
pump, and also to prevent all the water and steam in 
the boiler from escaping in case of accident to either 
the feed-pipe or pump, another valve, H, fig. 66, called 
a check-valve, is placed between the feed-pipe and the 
boiler. The construction of this valve is similar to 
that of the pressure and suction valves. It is inclosed 
in a cast-iron or brass case, II All of these valves 
have cages in which they work and which also act as 
stops, which prevent them from rising from their seats 
further than a certain distance. This distance is called 
their lift, and the successful working of the pumps de- 
pends very much on the amount of lift which the 
valves have. This is usually from ^ to J inch. 

Over the pressure-valve G is a chamber, J, called an 
air chamber. When water is forced into this cham- 
ber, it is obvious that as soon as it rises above the 
mouth of the pipe E, the air above the surface, c d, of 
the water will be confined in this chamber. This 
confined air, being elastic, will be compressed and ex- 
panded by the pressure of the water, so that it forms 
a sort of cushion, which relieves the pump and the 
pipes from the sudden shocks to which they are sub- 
ject, owing to the rapid motion of the pump-plunger. 

Another air-chamber, K K, is sometimes placed be- 
low the suction-valve F. The object of this is to sup- 
ply a cushion to relieve the suction-pipe from the 
shock which is caused by the sudden arrest of the mo- 
tion of the water in the pipe when the valve F is 
closed. When the pump-plunger is drawn out, the 
water flows through the valve F to fill the vacuum in 
the pump-barrel, A A, and consequently all the water 
in the suction-pipe is put in motion. As soon as the 



118 Catechism of the Locomotive, 

plunger returns, the valve F is closed and the motion 
of the water is suddenly arrested, thus producing more 
or less of a shock in the pipe D. When the water in 
the air chamber K K rises above the line a b, it is 
evident that the air above that line will be confined in 
the space surrounding the pipe L. This air then forms 
a cushion in the same way as that in the upper air 
chamber J does, which has already been explained. 
The advantages of the lower air chamber are, it is 
thought, more imaginary than real. 

Question 125. Hoiv can the pump be taken apart 
and the valves examined? 

Answer. By removing the bolts e, e, the upper air 
chamber can be taken off, and by taking out the bolts 
f, f, the lower one can be taken down, and the valves 
and cages removed. The check-valve Hcsrn be taken 
out by removing the bolts /, /, which hold up the valve- 
seat h and the valve and cage. 

Question 126. How can it be known whether the 
pump is forcing water into the boiler? 

Answer. To show this a cock, called a pet-cock, is at- 
tached to the upper air chamber in the position shown 
by the dotted circle m* By opening this cock, if the 
pump is working, a strong jet of water will be dis- 
charged from it during the backward stroke of the 
pump-plunger. If the pump is not forcing water into 
the boiler, or is working imperfectly, the stream dis- 
charged from the pet-cock will be weak, and the back- 
ward and forward strokes of the plunger will thus not 
be very definitely indicated by the discharge from the 
pet-cock. 



* The pet-cock is sometimes attached to the feed-pipe. 



The Boiler Attachments. 119 

Another small cock is often attached to the lower 
air chamber, or to the feed-pipe, to allow the water to 
escape from the pump in cold weather, when the en- 
gine is not working, so as to prevent it from freezing. 

Question 127. Why is it necessary to be able to regu- 
late the quantity of water which is forced into the boiler 
by the pumps ? 

Answer. Because when the engine is working hard, 
that is, pulling a heavy load up a grade, more steam 
and consequently more water are consumed than when 
it is not working so hard, and therefore more water 
must be forced in to supply the place of that which is 
used in the form of steam. If more water is forced in 
than is consumed, the water will rise and fill the 
steam-space and a part of it will then be carried into 
the cylinders without being evaporated. If too little 
water is forced into the boiler, the heating surface 
will not be covered, and there will consequently be 
danger that those portions which are exposed to the 
fire will be overheated and injured. 

Question 128. How is the supply of water which 
is fed into the boiler by the pump regulated ? 

Answer. By a cock in the suction-pipe called & feed- 
cock, which can be regulated by the locomotive run- 
ner, so that more or less water is supplied to the pump. 
There is also a valve in the water tank by which the 
supply of water can be regulated. 

Question 129. On what part of the locomotive are 
the pumps usually placed? 

Answer. They are usually attached to the frames 
behind the cylinders, and are worked by the piston- 
rod, as will be more fully explained hereafter; but 
they are sometimes placed inside of the frames, that 



120 Catechism of the Locomotive. 

is, between the wheels, and worked from an eccentric 
on one of the axles, and sometimes they are placed 
outside of the wheels near the back part of the loco- 
motive, and worked from short cranks attached to 
the crank-pins. 

Question 130. What provision is made for prevent- 
ing the water in the pumps from freezing in cold weather f 

Answer. Pipes which communicate with the steam- 
space of the boiler are attached to each of the suction- 
pipes, so that, by opening valves in the former, steam 
is admitted into the suction-pipes to heat the water in 
them. By admitting this hot water into the pump, it 
is kept warm, and the water is thus prevented from 
freezing. 

Question 131. What is an " injector "? 

Answer. It is an instrument in which a jet of steam 
from the boiler mingles with and forces a continuous 
jet of water into the same boiler against its own pres- 
sure. 

Question 132. What is the action of the injector and 
what are the names of its essential parts ? 

Answer. All injectors have certain parts in com- 
mon. These may be shown in the simplest form of 
instrument, as in the fixed-nozzle injector, a section of 
which (omitting all detail of construction) is shown in 
fig. 69. 

The steam from the boiler, passing through the pipe 
A, enters the receiving-tube G. Here it is joined by the 
water which enters the pipe B. The water condenses 
the steam in the combining-tube D, and a water jet is 
formed which is driven across the overflow space F F, 
and enters the delivery-tube H, thence past the check- 
valve I into the boiler. During the passage of the 



The Boiler Attachments. 



121 



water from D to H, as it passes across the overflow 
space F, if too much water has been supplied to the 
steam, some will escape at this point and flow out 
through the overflow nozzle G, while 
if too little water has been supplied, 
air will be drawn in at G, and carried 
into the boiler with the water. The 
names of the essential parts seem 
very applicable when we notice that 
steam is received from the boiler at 
C, combines with the water at D, and 
both are delivered to boiler through H. 
Question 133. Bow is the opera- 
tion of the injector explained ? 

Answer. Steam escaping from un- 
der pressure has a much higher ve- 
locity than water would have under 
the same pressure and condition. 
The escaping steam from the receiv- 
ing-tube unites with the feed-water in 
the combining-tube, and gives to this 
water a velocity greater than it would 
have if escaping directly from the water-space in the 
boiler. The power of this water to enter the boiler 
comes from its weight moving at the velocity acquired 
from the steam, and it is thus enabled to overcome the 
boiler pressure. 

This can be illustrated with a wooden croquet ball, 
which will float on the surface of water and will re- 
quire considerable force to make it sink. If, however, 
it is thrown violently into the water, it will sink to a 
considerable depth before its buoyancy will overcome 
its momentum, or actual energy. If, however, we were 
11 




Fig. 69. 



122 Catechism of the Locomotive. 

to take a very light, hollow wooden or india-rubber 
ball, no matter how violently we throw it into the water, 
it will not sink, because the total actual energy of any 

body IS PROPORTIONAL TO ITS WEIGHT MULTIPLIED 

by the square of its velocity, and therefore if 
we throw the hollow ball at the same velocity as the 
solid one, the former will still have much less energy 
than the latter. Now, as already stated, steam under 
a given pressure escapes from an orifice with a very 
much greater velocity than water. But steam being 
very light, if its weight is multiplied by its velocity 
its total energy will be comparatively small. Now in 
the injector, a portion of the high velocity of steam 
is imparted to the heavy water, because this water 
is presented to the action of the steam, not in a 
mass, as in the boiler, but in small quantity and in 
such a position that it can easily escape, so that it 
gradually acquires as high a velocity as the escaping 
steam can impart, and at the same time the steam 
is condensed, and therefore there is a heavy substance 
with a high velocity, whose actual energy is sufficient 
to overcome the pressure in the boiler. If the steam 
were not condensed we would have a comparatively 
light substance moving at a high velocity, which, as 
has already been explained, would have little actual 
energy, and would therefore not overcome the boiler 
pressure. 

Question 134. Does this involve any principle like a 
perpetual motion, or of work done without consumption oj 
power ? 

Answer. No, the steam escapes as steam, and is re- 
turned to the boiler as water with its bulk reduced, say 
1,000 times, and if it carries with it twenty times its 



The Boiler Attachments. 123 

weight of fresh feed-water, there would still be a loss 
of pressure or effective force in the boiler sufficient to 
do the work required in introducing the water. 

Question 135. Will the injector feed hot water? 

Answer. The instrument will not work when the 
feed-water is too hot to condense the steam, for the 
reasons given above, and the amount of water thrown 
is always the greatest when the feed- water is the 
coldest. Steam at a low pressure can be condensed 
more readily than steam of higher pressure, because it 
contains less heat. The feed-water may be used hot- 
ter to condense low steam than to condense high 
steam. In using the injector, the lower the boiler 
pressure the hotter may be the water within certain 
limits, the limit being the possible condensation of the 
steam. 

Question 136. Will a " Jixed-nozzle " injector, such 
as has been described, answer as a boiler feeder on loco- 
motives f 

Answer. It will answer at some one pressure of 
steam, to which pressure it may have been adapted in 
making the instrument, and at that pressure it will 
work admirably ; but it will not work satisfactorily at 
any other pressure, either higher or lower, and has 
not much range in quantity of water delivered. 

Question 137. What is required to make an injector 
work at different pressures f 

Answer. The instrument must be so made that the 
water passage between the receiving tube and the 
combining tube can be varied in size. This is usually 
done by making the combining and receiving tubes 
conical and moving the former to or from the latter, 
thus contracting or enlarging the water space. Such 



124 Catechism of the Locomotive, 

adjustment must be made at each change of steam 
pressure in the boiler. If this adjustment is made by 
hand, as in some kinds of injectors, it requires constant 
attention, if the steam pressure varies frequently. 

Question 138. How has this regulation been accom- 
plished without such attention ? 

Answer. In the self-regulating injector, fig. 
70, by using the escape water at overflow to push the 
combining tube towards the receiving tube and the in 
draught of water at the same place to pull the com- 
bining tube away from the receiving tube. This can 
be explained as follows : 

The case G of the instrument has two inlets, one 
for steam, the other for water, the two being sepa- 
rated by the plate F F. Steam passes into the 
receiving tube A, and its escape is regulated by a 
taper-plug in the end of the rod B, moved by the 
handle H. At the upper end of the combining 
tube C, where it swells out into a bell mouth, is a 
piston 1ST N, sliding in the case. The lower end at 
C is guided by the upper end of the delivery tube D. 
The delivery tube D is stationary. The overflow 
opening is at 0. The action of this instrument may 
be thus described: Steam entering the receiving tube 
A escapes through its lower end when the plug B 
has been drawn back. It unites with the water sur- 
rounding it in the space N JSf, is condensed and passes 
with the feed-water into the delivery tube 2), and 
thence into the boiler. If too much water enters the 
combining tube, some will escape at the overflow 0, 
and filling the space below the piston JV JV, will force 
the combining tube up toward the receiving tube, 
and, thus contracting the space between them, will 




Fig. 10k 



IV 



126 Catechism of the Locomotive. 

diminish the water supply; while, if it gets too little 
water in this space, it will take some in at the over- 
flow 0, and thus draw down the piston X N, and 
enlarge the space, giving more water to the instru- 
ment. This self -regulating principle enables the in- 
strument to continue working efficiently, no matter 
how much the steam pressure in the boiler varies. 

Question 139. Hoio do you start this Mncl of in- 
jector ? 

Answer. The instrument just described is the 
latest form of self -regulating injector, manufactured 
by Messrs. Wm. Sellers & Co., and is called by its 
makers the Injector of 1876. It is started and stopped 
by a simple movement of the lever H. This lever 
H moves a cross-head /, on the guide-rod J; it 
also, by means of stops T and Q, on rod L, opens 
and closes the starting-valve K. In fig. 70 the in- 
strument is shown shut off, and with the starting- 
valve K open. On the rod B are two valves, a 
small one W and a larger one X. A stop or collar is 
shown a short distance beyond the large valve X. 
If the lever H be drawn back until this collar comes 
in contact with the valve K, it will have raised the 
valve TFfrom its seat, and steam will escape through 
a small passage in the centre of the conical regulat- 
ing plug. The steam so admitted is sufficient to lift 
the water, which will then be driven through D, and 
past the valve K, and escape at P. Drawing back 
the lever H to the end of its stroke, after the water 
has been lifted, the large valve X is raised, and the 
lug on the lever H, coming in contact with the stop 
T, on the rod X, the valve iTis closed. The jet is 
fully established and the water is driven into the 



The Boiler Attachments. 127 

boiler. At the entire end of stroke of the lever H, 
the latch V falls into notches on the rod J, when, 
as the lever is moved forward toward the position 
shown in fig. 70, this latch will click over the notches 
and hold the lever in any desired position between 
the maximum and minimum delivery. 

Question 140. What attachments are needed be- 
sides the instrument to render it effective f 

Answer. A globe-valve should be placed in the 
steam pipe leading to the injector, to be closed only 
when there is occasion to remove the injector when 
steam is up, and in cold weather, to prevent the con- 
densation of steam in the pipes at the end of its 
trips. During all the working time of the injector, 
this valve should be wide open. 

Question 141. In what position, and in what lo- 
cation on the engine should the injector be placed ? 

Answer. On the right hand side, high enough up 
to have an air chamber below the injector, above the 
top of the water in the tank when the latter is full. 

Question 142. What is required to Tceep the in- 
strument in working order 9 

Ansioer. Constant use is better than occasional 
use. Having two injectors on the same engine, 
one on each side, the one on the runner's side will 
be used while running. The one on the other side 
should be used when standing. All pipe connections 
must be tight, so as to prevent the leaking of air. 
The pipe carrying steam to the instrument should 
be from such part of the boiler as will insure the use 
of dry steam, and the waste pipe must not be con- 
tracted. The instrument represented in the engrav- 
ing is the injector of 1876, manufactured by Messrs. 




Fig. 71. 
Scale. X in. = 1 foot. 



LIST OF PARTS DESIGNATED BY LETTERS OF REF- 
ERENCE IN FIG. 71. 

A, Furnace Door. 

B, B, Driving Wheels. 

C, Driving A xie. 

D, D, Suction Pipes. 

E, Ash Pan Damper. 

F, F, Foot Steps for getting on and off the Locomotive. 

G, G, Hand Holds for getting on and off the Locomotive. 
H, I, Cab. 

J, J, Doors in front of Cab. 

K, K, Windows in front of Cab. 

L, Steam Gauge. 

M, Spring Balance. 

N, Steam Gauge Lever, 

0' O, Throttle Lever. 

P, Water Gauge. 

Q, Stand for Tallow Can. 

B, Drip Pipe for Gauge Cock. 

T f T, Rod for operating Feed Cocfe* 

T\ Regulator tor Feed Cock. 

U V, Reverse Lever. 

W, Whistle. 

X, Blow-Off Cock. 

Z, Z, Frames. 

a, a, Heater Cocks. 

a, a', Heater Pipe. 

b, Blower Cock. 

c, c, Oil Cups for oiling Main Valves. 

d, Handle for opening Valves in Sand Box. 

e, e, Handles for opening Pet Cocks. 

/, Handle for opening Cylinder Cocks. 

g, Whistle Lever. 

h,' Whistle Handle. 

h, Rod connecting Whistle Handle to Whistle Leveto 

j, Handle for left hand Feed Cock. 

m m, Lever for shaking Grate Bars. 

n, Bell Crank for opening front Ash Pan Damper. 

o, o, Check Chains. 

p, Pipe for carrying off water from Gauge Cooka 

s, s, s, s, Gauge Cocks. 

w, Handle for opening Blow-Off Cock. 



130 



Catechism of the Locomotive. 



William Sellers & Co. of Philadelphia. Beside this. 
Mack's and several other kinds of injectors are now 
used. 

Question 143. How can the height of the water in 
the boiler be known f 

Answer. Two appliances are used by which the 
height of the water in the boiler can be observed. 
These are : 1. Gauge or try cocks. 2. The glass wa- 
ter gauge. 

Every locomotive is provided with four or more 
gauge-cocks, which are usually placed at the back end 
of the boiler, where they can easily be seen and 




Fig. 72. Scale |. 



The Boiler Attachments. 131 

reached. These cocks, s, s, s, s, are shown in fig. 
71, which represents the hack end of a locomotive, 
and to which frequent reference will he made. They 
are also shown on a larger scale in fig. 72, which rep- 
resents the end plate of the hoiler in section. They 
communicate with the inside of the hoiler and are so 
placed that one is three or four inches ahove the other. 
The two upper cocks are placed above the point where 
the surface of the water should be when the engine is 
working, and the two lower ones below it, so that the 
upper ones communicate with the steam space and 
the lower ones with the water. When these cocks are 
opened, if the water. is at its proper height, steam is 
discharged from the two upper ones, and water from 
the two lower ones. 

When a gauge-cock which communicates with the 
steam space is first opened, it is usually filled with 
condensed water, so that it should usually be kept 
open for a little while until this water is discharged. 
If the upper cocks are opened and continue to dis- 
charge water, they indicate that there is too much wa- 
ter in the boiler ; on the other hand, if steam is dis- 
charged when the lower cocks are opened, then there 
is too little water in the boiler, and the heating sur- 
face is in danger of being exposed to the fire without 
being covered with water, and consequently overheated, 
or as it is called " burned," and so injured as to be- 
come too weak to bear the strain to which it is sub- 
jected by the pressure of the steam. There is then 
great danger that the crown sheet may be crushed 
down by the pressure of the steam above it, or that 
the boiler may be exploded. Even if no accident 
occur, the boiler is in great danger of permanent 



132 Catechism of the Locomotive, 

injury from overheating when the water is allowed to 
get too low. 

Below the gauge-cocks s, s, s, s, fig. 71, an in- 
clined cylinder, R, called a drip-pipe, is placed with 
openings to receive the water and steam which are 
discharged from the cocks. This water is conducted 
away by the pipe p. 

The water-gauge, P, fig. 71, which is shown in sec- 
tion in fig. 73, consists of an upright* glass tube, a a, 
which is from one-half to three-quarters of an inch 
in diameter, and from 12 to 15 inches long. The 
glass is about one-eighth of an inch thick. At its 
ends it communicates with the steam and water of the 
boiler through brass elbows, b, c. The openings in 
these elbows, which communicate with the boiler, are 
closed by the valves or plugs, d, e, which are worked 
by screws and handles, f, g. The glass tube, when it 
is attached to the elbows, is made steam-tight by rub- 
ber rings, which are pressed tight around the tube by 
packing-nuts, h, i. The elbows are provided with the 
valves, d, e, so that in case the glass tube breaks the 
steam and water can be shut off, so as not to escape 
through the elbows. The lower elbow is provided 
with a blow-off cock, k, through which any sediment 
or dirt which collects in the glass tube or elbows can 
be blown out. When the valves in the upper and 
lower elbows are opened the steam flows into the glass 
tube through the upper one, and water through the 
lower one, and the water assumes a position in the 
glass tube on a level with the surface of that in the 
inside of the boiler; that is, the position of the water 

♦Sometimes these tubes are, for convenience, inclined, as shown in 
£g. 71. 



The Boiler Attachments, 



133 



in the boiler becomes visible in the glass tube. On 
account of the constant variations of the water in the 
boiler, the column of water in the glass never remains 




Fig. 73. 
$cale, 3 in.=l foot, 



134 Catechism of the Locomotive. 

stationary, but plays up and down as long as the 
boiler is working. But if the communication between 
the glass tube and the boiler is closed, then the water 
in the tube becomes stationary and the water gauge is 
useless. In order that there may be no obstruction of 
the glass tube by mud or dirt from the water, it must 
be blown out often. To do this the lower valve, e, is 
closed, and the blow-off cock, k, and the steam valve, 
d, are opened. The steam pressure in the tube on top 
of the column of water will force it out of the blow-off 
cock, and the mud and dirt will be carried with it. 

If from any cause the glass tube is broken, first of 
all the water-valve e should be closed and then the 
steam-valve d, so as to prevent the hot water and 
steam which will escape from the broken glass from 
scalding those who are working the engine. By un- 
screwing the nuts h and i the old glass can easily be 
removed and a new one substituted in its place* Care 
should be taken in putting in new glasses not to screw 
the packing nuts down any more than just sufficiently 
to make the rubber rings steam-tight around the glass 
tubes. If they are screwed too tight they are apt to 
produce a strain on the tube, so that the slightest ex- 
pansion by heat or contraction from cold will break it. 

Question 144. How is the steam pressure in boilers 
prevented from exceeding a certain limit f 

Answer. By what are called safety valves. These 
consist of circular openings, a, fig. 74, about three 
inches in diameter placed usually on the top of the 
dome,f and covered by a valve, b, which is pressed 



♦Extra glasses should always be carried with an engine so as to be sub- 
stituted in case of accident to the one in use. 
t One of these, v, is shown in fig. 41. 



The Boiler Attachments. 



135 



down either by a lever, c c{ and spring, d, as shown in 
fig. 74, or by a spring alone, as in fig. 76. Two of 
these valves are usually placed on the top of the dome> 
so that if one gets out of order the other one will allow 



Fig. 74. 
Scale 1£ in.=l foot. 
fi — . 



nk 




Fig. 75. 
Scale 1J in.=l foot. 



136 Catechism of the Locomotive. 

the steam to escape as soon as its pressure exceeds 
that which, it has been decided, the boiler can safely 
bear. This pressure, in locomotive boilers, is usually 
from 100 to 130 pounds per square inch. 

Question 145. How is the amount of pressure which 
must bear on top of a safety-valve determined? 

Answer. This pressure is determined by multiply- 
ing THE AREA OF THE OPENING FOR THE VALVE 
IN SQUARE INCHES BY THE GREATEST STEAM PRES- 
SURE, IN POUNDS PER SQUARE INCH, WHICH THE 

boiler is intended to bear. Thus, if the open- 
ing for a safety-valve is three inches in diameter, 
its area will be seven square inches, and, therefore, if 
the greatest steam pressure which it is intended that 
the boiler shall bear is 100 lbs. per square inch, 
the valve must be pressed down with a pressure 
equivalent to 7x100=700 pounds. If the pressure 
on the valve is produced by a lever, as in fig. 74,* 
then the total weight of the safety-valve must be 

MULTIPLIED BY THE SHORT ARM OF THE LEVER, 

(or the distance A between the centre of the fulcrum 
e and that of the load/,) and divided by B, the 

TOTAL LENGTH OF THE LEVER. In fig. 74 the short 

arm of the lever is 3J inches, and the whole length 
35 inches ; therefore if the valve is to be pressed down 
with a pressure of 700 pounds, the pressure on the end 
of the lever would be calculated as follows : 
700x31 



35 



=70 lbs 



The spring d must therefore pull down on the end 
of the lever with a tension equal to 70 pounds. When 

* The lever is represented in the engraving with a piece broken out, in 
order to save room. 



The Boiler Attachments. 137 

the pressure of the spring bears directly on the 
valve, as shown in fig. 76, then the tension of the 
spring must be just equal to the pressure on the valve. 
This tension is produced by screwing down the nuts, 
c, c. The spring d, which produces the requisite 
pressure on the end of the safety-valve lever, fig. 74, 
is arranged inside of two cylinders, g and h, which 
slide over or into each other like the sections of a tele- 
scope. This arrangement is called a spring-balance. 
The spring, d, is attached to the covered ends and 
draws them towards each other. The upper cylinder 
g is connected by a rod, i, to the flattened end of the 
lever c', which has a hole drilled through it to receive 
the rod. The other end of the rod is screwed into the 
upper cylinder g. This rod is sometimes arranged so 
that it can be either lengthened or shortened by the 
nuty. By lengthening or shortening the distance, 
the tension of the spring is either diminished or in- 
creased. The lower cylinder of the spring-balance, 
represented in fig. 74, is attached to a lever, m, which 
is fastened to the back of the steam-gauge k. This is 
shown more clearly by fig. 75, which represents the 
back of the gauge, and also the lever, / m, whose ful- 
crum is at m. The spring-balance is attached to the 
lever at k. By drawing down the lever the tension of 
the spring is increased, and by raising it up it is di- 
minished. The lever is held in any desired position 
by the latch, n, and the ratchet r r. By this con- 
trivance, which is employed on the engines built at the 
Grant and also at the Baldwin Locomotive Works, 
the pressure on the valve can at once be either in- 
creased or diminished, which it is often desirable to 
do, especially when an engine is not at work. The 



138 Catechism of the Locomotive, 

spring-balance is shown in fig. 71, and is indicated by 
the letter M and the lever by N. Unless the press- 
ure of the steam exceeds that on top of the valve, it 
will of course not be opened. As there is always dan- 
ger that a safety-valve or some of its attachments 
may become corroded or otherwise disordered, so that 
it will not act promptly or with certainty, it is desira- 
ble to open it frequently, so as to be sure that it is 
in good working order. To do this the pressure on 
the valve must be reduced below that in the boiler, 
which can very conveniently be done with the spring- 
balance lever which has been described. 

The lower cylinder of the spring-balance sometimes 
carries an index or pointer, t, fig. 74, which protrudes 
through a slot in the cylinder g, and indicates the 
amount of pressure of the spring on a scale marked 
along the slot on the outside of the cylinder. If it is 
desired that the safety-valve should open when the 
steam pressure reaches 100 or any other number of 
pounds per square inch, the spring-balance is subjected 
to a tension which will bring an amount of pressure 
on the top of the safety-valve equal in pounds per 
square inch of its surface to that of the steam pressure 
desired.* 

There should always be some provision made which 
will render it impossible to increase the steam press- 
ure beyond that which it has been determined that 
the boiler will safely bear. This is usually done by 
arranging one of the safety-valves with a lever, as 
shown in fig. 74, and the other without, like that in 
fig. 76. The latter is often covered and sealed or locked 



# In loading a safety-valve allowance must always be made for the 
weight of the lever and the valve. 



The Boiler Attachments. 



139 



up, so as to be beyond the control of the locomotive 
runner. 

The safety-valves are usually fitted into conical 
seats, S S, figs. 74 and 76, so as to be perfectly steam- 
tight, and are made with wings or guides, t, t, the 
form of which is shown in the sectional plan A, figs. 
74 and 76, under the valve. These guides are in- 
tended to keep the valves in the proper positions in 
relation to their seats. 

As soon as the steam pressure under the valves be- 
comes greater than the pressure of the springs on top 
of them, the valves will be lifted up and the steam 
will escape until the pressure in the boiler is relieved. 
It will be seen, however, that although the surface of 
the valve which is exposed to the pressure of the 
steam is equal to the area of the opening for the valve, 
after it is lifted from its seat and the steam escapes 
all around the edge, a larger surface will be exposed 
to the pressure of the escaping steam. For this rea- 




Fig.76. Scale J. 



140 Catechism of the Locomotive. 

son ; it will be found that after a valve is opened steam 
will escape, or u hlow off," as it is termed, until the 
pressure is several pounds lower than it was when the 
valve first opened. Advantage has been taken of this 
fact in the valve shown in fig. 76, which is called the 
"Richardson" valve, which is now much used. The 
top of this valve is made larger in diameter, so as to 
expose more area to the escaping steam. Grooves 
are also made around the edge of the valve and the 
seat. These, it is claimed, produce some sort of reflex 
action of the steam, which keeps the valve open longer 
than it otherwise would be. 

Question 146. Now is the steam pressure in the boiler 
indicated f 

Answer. By an instrument called a steam-gauge. 
There are a great variety of such instruments made, 
but they may all be divided into two classes, and 
they all operate upon one of two principles. In the 
one class the pressure of the steam acts upon a dia- 
phragm or plate of some kind, as shown in fig 77, 
which represents a section of a gauge of this kind j 
a b is a metal plate made with circular corrugations, 
as shown in section and also by the shading in fig. 78, 
which represents a front view of the gauge with a part 
of the dial-plate removed. The steam enters by the 
pipe c and the small opening d, and fills the chamber 
e behind the metal plate or diaphragm. The corruga- 
tions of the latter give it sufficient elasticity, so that 
when the pressure is exerted behind it, it will be pressed 
outward by the steam. If it were flat, it is plain that 
it would not yield, or only to a very slight degree, to 
the pressure of the steam. In the centre of the dia- 
phragm on the outside is a pin or stud, /, which bears 



The Boiler Attachments. 



141 



against the plate. This stud is attached to a bent 
lever or "bell-crank"* g h k, whose fulcrum is at h. 
To the outer end, k, a rod, I, figs. 77 and 78, is at- 
tached, the lower end of which is connected to the 
short arm m of a toothed segment, n, whose fulcrum is 
at o. This segment gears into a small pinion, p, which 
is attached to a spindle or shaft, which carries a poin- 




Fig. 78. Fig. 77. 

ter, fig. 78. It is obvious now that if the diaphragm, 
a b, is pressed outward, it will move the bent lever 
k h g, the motion of which will be communicated by 
the rod I to the toothed segment n, which will in turn 
revolve the pinion p, and thus move the hand or index. 
We have selected for this illustration one of many 
forms of this kind of gauge. The mechanical appli- 
ances for communicating the motion of the diaphragm 

* A bell-crank is a lever with an elbow in it. 



142 



(JdUchimi of che Locomotive. 



to the index or pointer are different in the gauges 
made by different manufacturers. The form of the 
diaphragm also differs. In some cases it is made of 
a metal plate ; in others a spiral spring is used, cov- 
ered with india-rubber to make it steam-tight. The 
steam-gauge represented by figs. 77 and 78 is the 
form manufactured by M. B. Edson, of New York. 




Fig. 79. 

In the other class of gauges, shown in fig. 79, the 
steam acts upon a bent metal tube, a b c, usually of a 
flattened or elliptical section. It may not be known 
to all readers that if a tube bent, say in the form of 
the letter U or C, is subjected to the pressure of a 
liquid or gas on the inside, the force exerted by the 
pressure has a tendency to straighten out the tube. 



The Boiler Attachments. 



143 



This is due to the tendency which a tube of an ellip- 
tical or flat section has to change the shape of the lat- 
ter and approximate to a circular form when the in- 
side is subjected to a pressure. Thus let A B, fig. 80, 
represent a cross section, and a b d c, a longitudinal 
section of a part of such a tube contained between 
two radii, a and b, drawn from the centre of 
the curye in which the tube is bent. If now we sub- 
ject tho inside of A B to a pressure it will have a ten- 

._„ c 




iJg. 



144 Catechism of the Locomotive. 

dency to assume the form of the circle G D, and 
would then be represented in the longitudinal sec- 
tion by the dotted lines a' b' d' c'. If now we draw 
radial lines through a' c / and b' d', it will be found 
that they intersect at (/, instead of 0, which was the 
original centre of the curve of the tube. It will be 
seen that as the section of the tube approximates to 
the form of a circle, the portion a b which is out- 
side the curve will be moved farther from the centre, 
while the other side, c d, is moved nearer to it. As 
indicated by the radial lines, when this occurs either 
the outside must be lengthened and the inside shor- 
tened, to conform to the radial lines a and b 0, or 
else the tube will be straightened so that the radial 
lines will assume the position af 0' and b' 0'. 

The phenomenon of the straightening of the bent 
tubes of steam gauges is frequently attributed to the 
difference between the area of the inside and outside 
of the curve. This error was shared by the writer, 
until the fallacy of the reasoning which supported it 
was pointed out to him. 

In the gauge represented in fig. 79, (in which the 
dial-plate is removed), one end, c, of the tube is attached 
at d to a lever which has a toothed segment, e, at 
the other end. The end a of the tube is connected 
with the lever at./! The connection at d, therefore, 
forms the fulcrum of the lever. It is obvious that as 
the two ends of the bent tube are forced apart by the 
steam pressure, the lever and the segment have motion 
imparted to them. The latter gears into a pinion on 
the spindle of the index or pointer, r r, which thus 
indicates on the dial the degree of pressure in the 
tube. The latter is connected with the boiler by a tube 



The Boiler Attachments, 145 

attached at g. Various forms of this kind of steam- 
gauge are also made, but all act on essentially the 
same principle. 

The position of the steam-gauge on the engine is 
shown at M, in fig. 71. 

Question 147. Why is the pipe which connects the 
steam-gauge with the boiler bent as shown in fig. 71 ? 

Answer. To prevent the hot steam from coming in 
contact with the metal plate or tube, as it is found 
that the heat of the steam affects their elasticity. 
When a bent tube is used, the steam from the boiler 
is condensed and fills the bent portion so that when 
the steam pressure comes on the surface of the water 
it forces it up the other leg of the tube into the gauge. 
A cock is attached to this pipe so that the steam can 
be shut off in case the gauge should get out of order 
or require to be removed while there is steam in the 
boiler. 

Question 148. How can the accuracy of a steam- 
gauge be tested? 

Answer. When the gauge is in good working order, 
the index or pointer moves easily with every change 
of pressure in the boiler, and if the steam is shut off 
from the gauge, the index should always go back to 0. 
In order to determine the accuracy of its indications, 
however, they should be tested with a column of mer- 
cury. This consists of a long, vertical tube, termina- 
ting at its base in a closed vessel filled with mercury. 
The gauge is then attached to the top of this vessel 
and water or oil is forced into the vessel on top of the 
mercury and into the gauge. A pressure of one 
pound per square inch will force up the column of the 
mercury 2.04 inches, so that by graduating the tube 
13 



146 Catechism of the Locomotive. 

into spaces that distance apart, the divisions will indi- 
cate the pressure in pounds per square inch. Thus, a 
pressure of 50 pounds would force up the column of 
mercury 102 inches, and with 100 pounds pressure 
the column would rise 204 inches, and therefore, 
when the mercury reaches these or any other points, 
the steam-gauge, if it is accurate, should indicate 
equivalent pressures. 

The ordinary steam-gauges are very liable to get 
out of order, and therefore they should be frequent- 
ly tested to ascertain whether their indications are 
correct. 

Question 149. What is the steam whistle, and for 
what purpose is it used ? 

Answer. The steam-whistle, W, fig. 71, and shown in 
section on a larger scale in fig. 81, consists of an in- 
verted metal cup or bell, A, made usually of brass. 
The lower edge of this cup is placed immediately 
over an annular opening, a a, from which the steam 
escapes and strikes the edge of the cup or bell, which 
produces a deep or shrill sound, according to the size 
or proportions of the whistle. The annular opening 
a a is formed by the plate or cover, a a, which nearly 
fills the mouth of the cup B, which is attached to the 
stem c. The latter is screwed into the top, D, of the 
dome. Commiunication with the steam-space of the 
boiler is either opened or closed by a valve, b, which is 
attached to a sort of spindle, d, which extends upward 
inside of the stem c. This spindle does not entirely 
fill the opening in the stem c, so that the steam which 
enters when the valve b is opened rises and escapes 
through the holes e, e, e, into the cup B and out 
through the annular opening a a. The valve is opened 



The Boiler Attachments. 



147 



by the lever E, whose fulcrum is at f. The end g of 
this lever is connected by a rod, h, figs. 81 and 71, 
with the cab, and by a suitable handle or lever, h' h', 
fig. 71, it can be opened and the whistle be blown 




Fig. 81. Scale 1| in.=l foot, 
at any time by the locomotive runner or fireman to 
give signals to the trainmen or of the approach of a 
train to a station, or to warn persons to get off of the 
track. 

Question 150. How is a locomotive boiler emptied 
and cleaned ? 



148 Catechism of the Locomotive. 

Answer. One or two large cocks, called blow-off 
cocks, X, fig. 71, are placed near the bottom of the fire- 
box, either in front or behind, and sometimes on the 
side. By opening either of these the water in the 
boiler is blown out, and much of the loose mud and 
dirt is carried out with the water. The cock X, fig. 
71, is opened by a handle, w, which is connected with 
the cock by a rod. 

In order to clean out the mud and scale which are not 
entirely loose, what are called mud-holes or hand-holes 
are placed in the corners of the fire-box near the bot- 
tom. These are oval-shaped holes, about 4^ inches 
long and 2\ inches wide, and covered with two metal 
plates, one of which is put inside the boiler and the 
other outside, and fastened with a bolt through both. 
Another hand-hole is sometimes placed in the bottom 
of the front tube-sheet. When the boiler is emptied 
of water these hand-holes are uncovered, and as much 
dirt is removed as can be scraped out of these holes. 
A hose pipe is then inserted and a strong stream of 
water is forced in, which washes out nearly all the 
loose dirt, so as to leave the boiler comparatively 
clean. 

When the water is very impure, what is called a 
mud-drum^ M, fig. 41, is used. Much of the mud and 
dirt is deposited in this receptacle, from which it can 
easily be removed by taking off the cast-iron cover on 
the bottom of the drum. The cover is also provided 
with a blow-off cock, which is shown in the figure re- 
ferred to. 

Question 151. What other attachments are there to 
the boiler of a locomotive ? 

Answer. There are two cocks, a, a, fig. 71, called 



The Boiler Attachments, 149 

heater-cocks, which are connected with pipes to the feed- 
pipes D D, to admit steam to the latter to prevent the 
water in them from freezing. There is also another 
cock, b, called a blower-cock, which is connected to the 
smoke-stack by a pipe b, b. Steam is conducted through 
this pipe and escapes up the chimney in a jet, thus pro- 
ducing a draft when the engine is not working. This 
arrangement is called a blower and is used to blow the 
fire when the engine is standing still. The action of 
the jet is similar to that of the exhaust steam which 
escapes up the chimney, excepting that the steam from 
the jet escapes in a continuous stream instead of dis- 
tinct "puffs/' as it does when it is liberated alter- 
nately from one end of the cylinders and then from 
the other. 

T' is a handle which is connected by a rod, T' T, 
with the feed-cock (not shown in the engraving) in 
the pipe D. This cock can be opened or closed by the 
handle, and the supply of water fed into the boiler by 
the pump can thus be regulated. J is a handle on the 
other side of the engine, for regulating the working of 
the pump on that side. 

e, e are handles, also connected by rods with the 
pet-cocks on the pumps. These cocks can thus be 
opened or closed, and it can then be known whether the 
pumps are working. 

A is the furnace door, which is fastened by a latch. 
The latter has a chain, Q, attached to it by which it 
can be conveniently opened or closed. The door also 
has a circular register with six holes to admit air into 
the furnace. These holes can be opened or closed by 
the revolving circular disc shown in the engraving. 

Question 152. How are the grates constructed? 



150 



Catechism of the Locomotive. 



Answer. As has already been explained, they are 
made usually of cast-iron bars,* A, A, A, figs. 82 and 
83, called grate-bars. Pig. 82 is a plan, and fig. 83 a 
horizontal section of one form of grate. The bars in 
this kind of grate are usually cast in pairs, or some 




* In Europe and in some 
wrought iron. 



in this country they are mad* r* 



152 Catechism of the Locomotive. 

times three or more are cast together. They are made 
wider on the top than on the bottom edges, as shown 
in the section, fig. 83, so that cinders and ashes will 
fall through easily, and also to give free access to the 
air from below. They are usually from | to 1^ inches 
wide on the top, and about J inch on the lower 
edges. The spaces between the bars are made from J 
to 1^- inches wide. For burning wood the bars are 
placed comparatively close together and are station- 
ary, but for burning bituminous coal they are usually 
made so that they can be moved, in order to shake or 
stir up the fire, just as is necessary in an ordinary 
stove or grate fire. In the grate we have illustrated 
the bars, A, A, are cast in pairs, and run crosswise of 
the fire-box. The ends are made with a sort of jour- 
nals, b, b, which rest on two supports, B, B, called 
bearing bars, which have suitable indentations to re- 
ceive the ends of the grate-bars. The latter have 
arms, G, G, fig. 83, cast on the under side, to which a 
bar, D D, is attached. By moving this bar back and 
forth, the grate-bars have a rocking motion imparted 
to them, as shown in fig. 84. It is evident that in 
this way the fire over the whole surface of the grates 
will be disturbed or shaken. The bar, D D, is moved 
by a lever, m m, shown in fig. 71. An extension 
piece, not shown in fig 71, is used with the lever m m, 
so as to increase its length ; but it is removed after it 
has been used, so as not to be in the way of the fire- 
man. Grates which have movable bars are called 
shaking or rocking grates. A great variety of such 
grates are made and in use, to describe which would 
require more room than is available here. 

For burning anthracite coal what are. called water- 



The Boiler Attachments. 158 

grates are used. These consist of wrought-iron tubes, 
2 inches in diameter outside, which are fastened in 
the front and back plates of the fire-box and are in- 
clined upward from the front end, so that there 
will be a continued circulation of water through them 
to keep them cool and thus prevent them from being 
burned out by the intense heat of the fire. 

Question 153. How is thejire removed from the fire- 
box when it is necessary to do so f 

Answer. In bituminous coal burning engines, what 
is called a drop-door, E E, figs. 82, 83 and 84, is pro- 
vided for that purpose. This door is supported partly 
on journals, d, d, similar to those in the grate-bars, on 
which it can turn, and is held up or prevented from 
dropping by arms, e, e, attached to a shaft, F F. This 
shaft is operated by a lever, ff fig. 82, outside the 
fire-box. 

When the arms are in the position represented in 
fig. 83, the drop-door is held up in the place in which 
it is shown ; but when they are turned as in fig. 84, the 
door falls down so that the burning coal can be taken 
out of the opening at G, and, by raising up the ash- 
pan damper, H, fig. 84, can be raked out on the track 
or into p' ^able pits usually provided for this purpose. 
The drop-doors are sometimes perforated so as to ad- 
mit air to the fuel on top of them. 

The grates for burning anthracite coal usually have 
about four solid wrought-iron bars between that num- 
ber of tubes. These bars can be withdrawn, and the 
fire then falls into the ash-pan through the opening 
left by the withdrawal of the tubes. 

Question 154. How are the dampers of the ash-pan 
operated ? 



154 



Catechism of the Locomotive. 



Answer. They are connected by suitable rods and 
levers with two handles, /, I, fig. 71, which are raised 
or lowered, thus opening or closing the dampers. 






PART IX. 

THE THKOTTLE-VALVE AH D STEAM PIPES, 

Question 155. How is the steam admitted to and the 
supply regulated or shut off from the cylinders $ 

Answer. By a valve, h, fig. 41, called a throttle-valve^ 
which is usually placed at the end of the pipe I, near 
the top of the dome. Throttle-valves are sometimes 
placed in the smoke-box at the front end, n, fig. 41, of- 
the dry-pipe. Until within a few years they consisted! 
of plain slide-valves which covered openings similar 
in form to the steam-ports, hut smaller in size. The 1 
pressure on such valves is of course greatest when 
there is no steam underneath, which is the case when. 
the valves are closed. It is then very difficult to open 
them, and as it is important that the supply of steam 
admitted to the cylinders when the locomotive is started 
should be easily regulated, such valves are objection- 
able, and therefore the form has been introduced which; 
is illustrated in fig. 41, and also on a larger scale in 
fig. 85, which represents a longitudinal section of the 
throttle-pipe and valve. This is what is called a. 
double-poppet valve, and consists of two circular discs, 
a and b, which cover two corresponding openings in 
the end of the pipe 1. When these discs are raised 
up, as shown in fig. 85, steam flows in around their 
edges, as represented by the darts. It will be ob- 
served that the steam pressure in the boiler comes on. 






156 



Catechism of the Locomotive, 



top of the disc a and against the under side of b. The 
pressure on the one thus neutralizes or balances that 
on the other. If the two discs were of the same size, 
the pressure of the one would be exactly the same as on 
the other; but as they are joined together and are 
made to fit steam-tight on their seats by what are 
called countersunk joints ; their diameters must be some- 




The Throttle- Valve and Steam Pipes. 157 

what larger than the openings they cover. The only 
practicable way, therefore, by which the lower disc b 
can be introduced into the end h of the pipe / so as to 
cover the lower opening is through the upper opening 
a. For this reason the lower disc must be made 
smaller than the upper one, and therefore the 
pressure on the upper one, being in proportion to its 
size, has a constant tendency to close the valve. As 
it is of the greatest importance that a throttle-valve 





158 Catechism of the Locomotive, 

should remain closed after steam is shut off, and never 
be opened at any time accidentally, the arrangement 
described accomplishes just what is needed — that is, 
makes the valve work comparatively easily, and at the 
same time keeps it closed after the steam has been 
shut off. 

Question 156. How is the valve opened and closed? 

Answer. By a lever, / 0, called a throttle-lever, figs. 
85, 86* and 71. This lever is connected by a rod, d, 
called the throttle-stem, with a bell crank, i, the other 
arm of which works the rod c, to which the throttle - 
valve is attached. The rod d works through a steam- 
tight stuffing-box, f, in the back end of the boiler. 
The end of the throttle-lever is attached to two links, 
g, fig. 86, which are fastened by a pin to the stud h. 
These links have a slight vibratory motion, which 
enables the pin k, by which the lever 0' 0, is fastened 
to the rod d, to move in a straight line, which is 
necessary in order that the rod d may work steam- 
tight in the stuffing-box, f. The throttle-lever has a 
latch, I, which gears into a curved rack, n, so as to hold 
the lever and valve in any required position. This 
latch is operated by a trigger, m. Various other de- 
vices are used to fasten the throttle-.^ ver and thus 
hold it in any position required. 

Question 157. How are the steam pipes constructed? 

Answer. The steam, after it is admitted by the 
throttle-valve, as was explained tn answer to Question 
155, passes into the throttle-pipe I and the dry-pipe 
m m, fig. 41. At the front end of the dry -pipe a pipe, 
n, figs. 40 and 41, which divides into two branches 
like the top of the letter T and is therefore called a 
* Fig. 86 is a plan, showing the top of the valve and lever. 



The Throttle- Valve and Steam Pipes, 159 



T-pipe, is attached. The steam-pipes o, o, fig. 40, are 
connected to each of the two branches of the T-pipe at 
one end and to the cylinders at the other.* 

These pipes, being in the smoke-box, are exposed to 
great changes of temperature, and are therefore sub- 
jected to expansion by heat and contraction by cold. 
The joints are therefore constantly subject to disturb- 
ance by the contraction and expansion of the pipes 
and so are difficult to keep tight. It is also practically 
impossible to construct the boiler, the cylinders and the 
pipes with perfect accuracy, and therefore a small 
amount of adjustability and flexibility is necessary in 
the joints of the pipes. If, for example, the opening 
x in the cylinder, fig. 40, were either too near or too 
far from the cylinder of the engine, it would be neces- 
sary to move the end of the pipe o either to the right 
or to the left in order to connect it with x. If the 
joint of the upper end of the steam-pipe were attached 
to the T-pipe with a flat joint like that shown at a b, 




Fig. 87. Scale 1£ in.=l foot, 
fig. 87, it would be impossible to move the lower end 
of the steam-pipe either to the right or to the left 
without disturbing the joint and causing it to leak. 

* In fig. 40 the right-hand side represents a section through the steam- 
pipe o o, and. the left a section through the exhaust pipe e e. 



160 



Catechism of the Locomotive. 



For this reason these pipes are connected with what 
are called ball joints, fig. 88, that is, the end a b of one. 




Fig. 88. Scale 1| in.=l foot. 



of the pipes is turned into the form of a part of a 
sphere,* and the other end into a corresponding con- 
cave form. It is known that a sphere will fit into a 
corresponding socket in any position ; for example, an 
acorn in its cup or the bones at the hip or shoulder 
joints. If, therefore, the pipes are joined with such 
spherical or ball-joints as they are called, the lower end 
can be moved sideways several inches either way, and 
the joint will still be steam-tight if it is then firmly 
bolted together. Even after it is bolted together 
it will have so much flexibility that the expansion 
and contraction of the pipes will not cause it to leak. 
There is, however, still another difficulty. Although 
the lower end of the pipe, o o, fig 40, can, with a ball- 
joint above, be moved in any direction horizontally, 
yet if the pipe is too long or too short it is obvious such 
a joint will not permit it to be moved up or down. 
A joint with a flat surface, like that shown in fig. 87, 



* The dotted lines indicate what would be the form of the sphere if the 
pipe was solid instead of hollow. 



The Throttle- Valve and Steam Pipes. 161 

would, however, permit such motion in the pipe with- 
out leaking. If, for example, the steam-pipe were J 
of an inch too short, it might be drawn down that dis- 
tance, and if the upper joint were then screwed up it 
would still be steam-tight. In order, then, to get both 
vertical and lateral flexibility in the joints of the 
steam-pipes, a ring, a b, fig. 89, is interposed between 




Fig. 89. 



the pipes. One side of this ring is spherical and the 
other flat, so that the pipes can move either around 
the spherical part or slip up or down or sideways on 
the flat surface of the ring. In this way the pipes are 
flexible and adjustable in every direction, and for all 
kinds of motion caused by expansion, or which may 
be needed when the parts are put together. Some- 
times the joints at one end only of the steam-pipes are 
made in this way, and the other is connected with a 
simple ball-joint. 

In designing these joints their form should be 

drawn with a radius, c d, fig. 88, from one centre, c, so 

that the surface of the joint will form a part of a 

sphere. If they are drawn from two centres, as is 

14* 



162 Catechism of the Locomotive. 

sometimes done, it is obvious that the surface of the 
joint will not be a part of a sphere, and therefore will 
not have the requisite flexibility. The surfaces of the 
joints are carefully turned to the proper form, and 
then made steam-tight by scraping or grinding them 
with emery and oil, and the pipes are then fastened to- 
gether with bolts, g, g, fig. 89, and flanges, ff, cast on 
the pipes. 

Question 158. Bow we the exhaust pipes con- 
structed ? 

Answer. They are made of cast iron. When two 
nozzles are used they are generally cast together, as 




Fig. 90. Scale 1| in.=l foot. 

shown in fig. 90. When only one is used, the form of 
the pipes resembles somewhat that of an inverted let- 
ter \, as shown in fig. 91, so as to cover the two open- 
ings which connect with the cylinders. The tops of 
these pipes have rings or bushings, a a, fitted into 
them, which are held by set screws, b, so that they can 
easily be removed and others with larger or smaller 
openings be substituted. If the openings in the 
exhaust-nozzles are small, the steam must be dis- 



The Throttle- Valve and Steam Pipes, 168 

charged at a higher rate of speed, in order to exhaust 
all that is in the cylinders, than if the blast orifices 
are larger. Therefore, if the latter are reduced in 
size, the draft becomes more violent, but at the same 
time the back-pressure in the cylinder (which will be 
explained hereafter) is increased. It therefore be- 
comes necessary to adjust the size of the blast orifices 




Fig 91. Scale 1* in. =1 foot. 
with the greatest care, so as to have them just small 
enough to produce the required draft and yet leave 
them as large as possible, so as to reduce the back- 
pressure. For these reasons what are called variable 
exhausts are sometimes used. In these the blast orifice 
can be increased or diminished at pleasure, and thus 
regulated to suit the conditions under which an engine 
is working. A great variety of such devices has been 
used, but now nearly all have been abandoned for the 
simpler arrangement described, which is not variable 
when the engine is working. 



PAET X. 

THE CYLINDERS, PISTONS, GUIDE-RODS 
AND CONNECTING-RODS. 

Question 159. How are the steam cylinders con- 
structed f 

Answer. They are made of hard cast iron, and have 
the steam and exhaust ports and valve-seats cast with 
them. The harder the iron the better will the cylin- 
ders withstand the wear of the pistons and valves, but 
they must at the same time be made soft enough, so 
that after they are cast the inside can be bored out 
perfectly cylindrical, the ends turned off, the bolt- 
holes drilled, and the valve-seats planed smooth. 

Eig. 92 represents a longitudinal section through 
the centre of the cylinder and steam-chest. Eig. 94 
is a plan of the same parts with the cover of the steam- 
chest and the valve removed. The left-hand side of 
fig. 95 shows a transverse section through the centre 
c d, fig. 92, of the cylinders, and the right side is a 
section through the steam-pipe G h, Jig. 94. The 
same letters indicate like parts in the three different 
views. 

The cylinders of locomotives in this country are 
now universally placed on the outside of the wheels, 
as has alread}^ been described. In order to fasten 
them securely together and to the boiler, they are at- 
tached to what is called a bed-plate or bed-casting, D D, 



The Cylinders, Pistons, etc. 165 

figs. 94 and 95, which is placed between them. Some 
builders make this bed-casting in a separate piece, 
and the cylinders are then bolted to it on the outside, 
about at the dotted lines, I, m, fig. 95. Others cast 
one-half of it with each cylinder, as shown in our en- 
gravings, and then bolt them together at the line i,j, 
which is the centre of the engine. The bed-casting 
is also bolted to the smoke-box by the flanges E, E. 
The cylinders are bolted to the frame F with bolts, m 
and k, fig. 95. 

After the cylinders are bored out, and the ends 
turned off, heads, A and B, figs. 92 and 94, are fitted 
with steam-tight joints to each end. These heads 
are fastened with bolts and nuts, a, a, a, to flanges, 
C, G. 

Question 160. How is the steam conducted to and 
from the cylinders ? 

Answer. Two pipes or passages are cast in each cyl- 
inder, the one, G G', fig. 95, for admitting steam into 
the steam-chest, and the other, H H', for exhausting 
it from the cylinders. The one G G / is called the 
steam-passage, and the other, H H', the exhaust-passage. 
The steam-passage terminates at one end with a round 
opening, G, figs. 94 and 95, to which the steam- 
pipe o, figs. 40 and 95 is attached inside of the smoke- 
box. At the other end it divides into two branches, 
G', G', fig. 94, each of which terminates in an open- 
ing, g, g', inside of the steam-chest. The steam is 
thus delivered at both ends of the chest, and can pass 
freely into each of the steam-ports. By making the 
cylinders in this way, they are exactly alike for each 
side of the engine, or, to use a shop phrase, there are 
(< no rights and lefts," so that a cylinder casting can be 



I 



The Cylinders, Pistons, etc. 169 

used for either side of the engine. This method of mak- 
ing cylinders has been adopted by a number of the prin- 
cipal builders in this country, but is by no means uni- 
versal. 

Question 161. How is the steam-chest constructed? 

Answer. It usually consists of two castings, one of 
which, J, figs. 92 and 94, is a square cast-iron box 
made open at the top and bottom. This rests on the 
top of the cylinder casting and is joined to the latter 
with a steam-tight joint. On top of it is a cast-iron 
cover, K K. The steam-chest and cover are held 
down by bolts, p, p, which are screwed into the cylin- 
der casting and have nuts on top. 

Question 162. How are the slide-valves made to work 
steam-tight on the valve-seats ? 

Answer. They are first planed off smooth, and then 
filed and scraped until the two touch each other over 
the whole of their surfaces in contact. The valve-stem 
v, fig. 92, works steam-tight through a stuffing-box on 
the steam-chest. 

Question 163. How are the valves and pistons oiled 1 

Answer. The oil is usually introduced into the steam- 
chest through a cock, c, fig. 92, called an oil-cock. 
From this cock it flows down upon the valve and is 
conducted by suitable holes and channels to the 
valve-face and from there through the steam-ports to 
the cylinder and piston. Sometimes, for greater con- 
venience, oil-cocks c, c, fig. 71, are placed inside of the 
cab and communicate by pipes with the steam-chests. 

The valves are oiled by pouring oil or melted tallow 

into the oil-cocks when the steam is shut off from the 

steam-chests and cylinders. When the pistons are 

working in the cylinders without steam, they create 

15 



170 Catechism of the Locomotive. 

a partial vacuum, so that if oil is then poured into 
the oil-cocks it will be sucked into the steam-chests, 
or, in other words, it will be forced in by the pressure 
of the air above it. Q, fig. 71, is a shelf attached to 
the boiler to receive an oil-can filled with oil or tallow, 
which is thus melted or kept in a fluid condition by the 
heat of the boiler. 

Question 164. How are the cylinders and steam- 
chests protected so as to prevent, as far as possible, the heat 
in the steam from being lost t 

Answer. The sides of the cylinders are covered with 
wood, w, w, w, fig. 95, called the cylinder lagging, and 
the wood is covered outside with Russia iron or brass, 
which is called the cylinder-casing. The ends of the 
cylinders have light metal covers, called cylinder-head 
covers, made of cast iron, brass or sheet metal. The 
steam-chest is covered in a similar way so as to be 
surrounded either with a covering of wood or of con- 
fined air. Sometimes coarse felt is used for the pur- 
pose. The covering, excepting the cylinder lagging, 
is not shown in the engravings. 

Question 165. For what purpose are the cocks G, G, 
Jigs. 92 and 95, at each dhd of the cylinder, used ? 

Answer. They are used to exhaust the water which 
collects in the cylinders. When the engine is not 
working the cylinders and steam-pipes are all cooled 
off, so that when steam is first introduced into them 
a great deal of it is condensed until they become 
warmed. Water is also frequently carried over from 
the boiler with the steam. When this occurs the 
boiler is said to prime, or to "work water." This water 
and that produced by the condensation of steam collect 
in the bottom of the cylinder and will not escape 



The Cylinders, Pistons, etc. 171 

through the exhaust-pipes until the piston moves up 
so near to the end of the cylinder that the water will 
fill the whole space between it and the cylinder-head. 
As has already been stated, it will then escape so 
slowly that the momentum of the piston and other 
machinery is liable to " knock out " the cylinder-heads 
or even break the cylinder itself. The cocks C, G, 
called cylinder-cocks, are therefore placed in the under 
side of the cylinder, so that when they are open if 
there is any water in the cylinder it will escape 
through the cocks. They are therefore always opened 
when the engine is starting, or at any other time when 
there is any indication that there is water in the cyl- 
inders. 

Question 166. How are these cocks opened and 
closed ? 

Answer. A shaft, R R, figs. 92 and 94, which ex- 
tends across the frames, has an arm, R S, fig. 92, at 
each end. These arms are connected by rods, S T, with 
the handles of the cylinder-cocks. The shaft also has 
a vertical arm, R U, the upper end of which is con- 
nected by a rod with the cab. At the end of the rod 
is a suitable handle,/, fig. 71, by which the cocks can 
be either opened or closed at pleasure by the locomo- 
tive runner. 

Question 167. How is the piston-rod fastened to the 
piston ? 

Answer. It fits into a straight or tapered hole in the 
piston-head, in which it is fastened either with a key, 
k k, as shown in figs. 96 and 97,* or by a nut on the 
front side of the piston. 



* Fig. 96 is an end view of the piston with the follower-plate removed, 
^tg. 97 is a section through the centre. 



172 



Catechism of the Locomotive. 



Question 168. How is the piston constructed f 
Answer. It is made of two cast-iron pieces, B and G, 
fig. 97, the one, JS, called the piston-head or spider, to 
which the piston-rod D is attached. The other part, 
0, called the follower-plate, is bolted to the piston- 
head by the bolts c, c, called follower-bolts. The pis- 
ton-head has lugs or projections, d, d, d, fig. 96, cast 
on the inside, to which the follower plate is bolted. 
Hollow spaces are thus left between these lugs. 



A A 




A A 

Fig. 96. Fig. 97. 

Scale 1£ in.=l foot. 

Question 169. Bow is the piston made to work steam- 
tight in the cylinder ? 

Answer. By means of two rings, A, A, figs. 96 and 
97, called packing-rings. These rings are turned of 
the same size or a little larger in diameter than the 
cylinder. They are then cut open at one point in 
their circumference so that they can be pressed apart 
or expanded by the springs a, a, called packing springs^ 



The Cylinders, Pistons, etc. 173 

on the inside of the rings. These springs are pressed 
out by the nuts and bolts b, b, called packing-bolts and 
packing-nuts, so that when the rings wear they can be 
expanded so as to fill the cylinder completely. The 
place where the one ring is cut is placed opposite that 
of the opening in the other ring, or they are made to 
break joints, as it is called. This is done to prevent 
the steam which leaks through the opening where the 
one ring is cut from passing through to the other side 
of the piston. These rings are usually made of brass 
and have grooves, c, c, fig. 97, turned in them, which 
are filled with what is called Babbitt's metal. This 
metal is used because it is less liable to scratch the 
cylinders than brass alone. Another ring, 1 1, made of 
cast iron and as wide as the two brass rings, is placed 
inside of the latter and is intended to furnish a bear- 
ing for the springs, and thus distribute the pressure of 
the springs equally on the packing rings. This iron 
ring is also cut open at one point. 

Question 170. How is the piston-rod made to work 
steam-tight through the cylinder-head? 

Answer. By what is called a stuffing-box. This con- 
sists of a cylindrical chamber, r r, fig. 92, which is 
made about 1J inches larger in diameter than the pis- 
ton-rod. This leaves a space f of an inch wide all 
around the rod. This space is filled with hemp or 
some other fibrous material, called packing, saturated 
with oil or melted tallow. This packing is compressed 
by a hollow cylinder, s s, called a gland, the inside of 
which fits the piston-rod and the outside the stuffing- 
box. This gland is forced into the stuffing-box by 
nuts, t, t, which are screwed down on a flange, u, at- 
tached to the gland. The packing is thus compressed 
15* 



174 Catechism of the Locomotive. 

in the stuffing-box and forced against the piston- 
rod, which is made smooth and perfectly round and 
straight, and against the side of the stuffing-box, 
so that no steam can escape around the piston-rod. 
A brass ring or " bushing " is often put into the 
cylinder-head and in the gland where it touches the 
piston-rod,* because brass will bear the friction of the 
rod better than cast iron, and when it is worn out it 
can be removed and a new one substituted in its 
place. 

Question 171. Why is the end of the piston-rod 
made to work in guides f 

Answer. Because it must move in a straight line if 
it and the piston work steam-tight in the cylinder. 
By referring back to fig. 2, it is obvious that if a 
pressure be exerted against the piston B and commu- 
nicated to the crank-pin i^by the connecting-rod E, 
the latter, excepting at the dead-points, will exert a 
pressure either upward or downward, according to the 
direction the piston is moving. This pressure would 
bend the piston-rod if no provision were made to pre- 
vent it. For this reason, therefore, the end of the 
piston-rod is attached to what is called a cross-head, 
L, figs. 92 and 94, which works in guides, M, M. The 
cross-head is made of cast iron and has slides, N, N, 
figs. 93 and 94, one on each side, each of which works 
between a pair of guide-bars or rods, M, M, shown in 
section in fig. 93.f These guide-rods, or guides as 
they are called, are planed and finished with great ac- 
curacy so as to be straight and smooth, and are at- 
tached to the cylinder-head at one end, and to a sup- 

* Locomotive piston-rods are now usually made of steel. 

t Fig. 98 is a transverse section through the guides at », flg 92. 



The Cylinders, Pistons, etc. 



175 



port, 0, called the guide-yoke, which is fastened to the 
frame at F, fig. 94, and also usually attached to the 
hoiler. The guides are set with great care, so as to 
be exactly parallel with the axis or centre line of the 
cylinder, so that the cross-head will slide in exactly 
the same path that the piston-rod will if it moves in 
a straight line. If then the piston-rod and the con- 
necting-rod are attached to the cross-head, all the 
strain produced by the obliquity of the connecting- 
rod will be borne by the guides, thus relieving the 
piston-rod, and making it certain that it will move in 
a straight line. 

Question 172. How are the piston and connecting- 
rods attached to the cross-head f 

Answer. The end of the piston-rod fits into a ta- 
pered hole in the cross-head and is held by a key, w, 
figs. 92 and 94. The connecting-rod is attached to a 
pin, Q, called a wrist-pin, which is cast with the cross- 
head. 

Question 173. How is the wear of the slides lessened 
and compensated f 

Answer. Sometimes they are made with brass 
wearing pieces called gibs, shown at N, N, fig. 93, 
which are placed between the slides and the guides. 
These gibs can either be removed and new ones sub- 
stituted when they become very much worn, or by in- 
serting thin pieces of metal, called liners, between 
them and the cross-head, they will be spread apart so 
as to fill the space between the slides. The slides are 
now, however, oftener made without gibs, and have 
recesses either cast or drilled in them, which are filled 
with either Babbitt's metal or glass bearings, which 
latter are said to wear very well. The guides are 



176 Catechism of the Locomotive. 

bolted at each end to blocks, x, x, called guide-blocks, 
which can be planed off so as to bring the guides 
nearer together when they and the slides are worn. 
Sometimes liners are placed between the blocks and 
the guides, which can be removed when it is necessary 
to bring the guides nearer together. 

Question 174. Are the top and bottom guides worn 
alike ? 

Answer. No : the top guide in ordinary engines is 
worn the most, because the pressure of the slides is 
always on the top guide when the engine is running 
forward, and on the bottom guide when it is running 
backward. This will be understood by referring back 
to the series of figures from 11 to 24. It will be no- 
ticed that in the backward stroke of the piston, repre- 
sented by figs. 11 to 17, the strain on the connecting- 
rod tends to push the cross-head upward, and in the 
forward part of the stroke, figs. 18 to 24, the connect- 
ing rod pulls the cross-head in the same direction. If 
the crank turned the opposite way, this action would 
be reversed and the cross-head would then be alter- 
nately pushed and pulled downward, and the bottom 
guides would then be worn the most. As nearly 
all locomotives run forward more than backward, the 
tops guides are usually worn the most. 

Question 175. Bow are the slides oiled? 

Answer. Oil cups, n, o, figs. 92, 93 and 94, are placed 
about the middle of the top guide. These cups usually 
have a reservoir to hold a supply of oil, and are so 
constructed that it will be gradually fed on the slides, 
which are thus constantly and regularly lubricated. 

Question 176. How are the pumps worked from the 



The Cylinders, Pistons, etc. 



177 



Answer. The pump-plunger is attached to a projec- 
tion, W, figs. 92 and 93, called the pump -lug, cast on 
one of the slides of the cross-head. The plunger thus 
receives a reciprocating motion from the piston. 

Question 177. How are the connecting-rods made ? 

Answer. They are made of flat bars of wrought iron. 
The rods which connect the cross-heads with, the 
driving-wheels are called main connecting-rods, and 
the rods which connect or couple the driving-wheels 
together are called coupling-rods.* Fig. 98 represents 
a side view and a plan of a main connecting-rod. In 
the side view the end B, and in the plan both ends of 
the rod are shown in section. It is attached to the 
wrist-pin at A and to the crank-pin at B. Fig. 99 
represents similar views of a coupling-rod. To save 
room in the engraving each of these rods is repre- 
sented with a part of the middle broken away. The 
main rods are usually made wider at G, next the 
crank-pin, than at the other end, as it has been found 
that they are most liable to break at that end. The 
coupling-rods are now made either straight or some- 
what wider in the centre. 

Question 178. How are these rods prevented from get- 
ting loose on the pins from the wear of the latter in the in- 
side of the holes of the rods ? 

Answer. The ends of the rods are provided with 
what are called brass-bearings,^ or " brasses" c, d, and 
e,f. These brasses are made in pairs, so as to em- 
brace the pins, from each side. They are held by 
ID-shaped clamps, s s s, called straps, which are bolted 

* They are also often called side or parallel-rods, but the term coup- 
ling-rods is considered the best. 

t The portion of a shaft pin or spindle subjected to friction is called a 
journal, and the surface which presses or " bears " against it is called a 
bearing. 




* «L* 






Scale % in. =1 foot. 



The Cylinders, Pistons, etc, 179 

to the rods. When the brass-bearings become worn, 
they are taken out of the straps, and a portion of their 
surfaces of contact with each other is filed away, thus 
allowing them to come nearer together, and thereby 
reducing the size of the hole which receives the pin or 
journal. In order to prevent their being loose in the 
straps, tapered or wedge-shaped keys, k, k, which bear 
against the brasses, are fitted in the straps and rods. 
By driving down these keys the brass bearings are 
forced together, thus reducing the size of the hole for 
the journal, and making the rods fit tightly on the 
pins. A hard steel plate, shown by dark shading in 
the engraving, is sometimes interposed between the 
keys and the brasses to prevent the key from indent- 
ing the surface of the soft brass. As the keys are 
very liable to get loose and fall out, they are held 
either by screws and nuts, x, x, as shown in the en- 
graving, or by set-screws on the side of the rods. The 
whole arrangement of straps, keys and brasses is called 
a stub-end. 

Question 179. How are the journals of the crank- 
fins oiled? 

Answer. By oil-cups attached to the straps, above 
the journals, similar to the cups used on the guide- 
rods, but which are not shown in the engravings of 
the connecting-rods. Sometimes oil-cellars, as they 
are called, are attached to the under side of the straps. 
These are metal boxes, which are filled with oil, which 
is agitated violently by the rapid motion of the rods, 
and is thus applied to the journals through holes 
drilled in the straps. In order to confine the oil and 
prevent its leaking out around the journals of the 
coupling-rods, the brasses at m, m, fig. 99, are usually 



180 Catechism of the Locomotive. 

made so as to enclose the outside end of the crank- 
pin, which thus not only keeps the oil in, but excludes 
the dust. The brasses are usually lined with Babbitt's 
or some other kind of soft metal, which is thought to 
be less liable to heat from the friction of the journals. 

Question 180. Are the coupling-rods always made 
with stub-ends f 

Answer. No ; their ends are sometimes made in one 
piece — that is, without straps or keys. The holes which 
receive the crank-pins then have brass rings or bush- 
ings, as they are called, which fit tightly and are 
driven into the holes, and form the bearings on the 
pins. When these rings become worn they are 
driven out and new ones put in. 

Question 181. What is meant by the term lost motion f 

Answer. It is used to designate the wear of ma- 
chinery, which causes a loss of motion in some of the 
parts. Thus if the bearings of the main connecting- 
rods are worn, the piston must move a distance equal 
to the wear at each end of the stroke before it moves 
the crank-pin. Lost motion might therefore be called 
the looseness of the parts. When we speak of taking 
up the lost motion, we mean making parts which were 
loose fit tightly. 



PAET XI. 
THE VALVE-GEAR. 

Question 182. What is meant by the valve-gear of a 
locomotive ? 

Answer. By the valve-gear is meant the arrange- 
ment of eccentrics, rods, links, rockers, etc., by which 
the valves are moved and their motion regulated. 

Question 183. What is required of the valve-gear in 
working a locomotive f 

Answer. It must he so arranged that the locomotive 
can be run either backward or forward, and so that 
the motion of the wheels can be reversed quickly and 
with certainty. It should enable the runner to em- 
ploy the greatest power of the engine by admitting 
steam into the cylinders during the whole or nearly the 
whole of the stroke of the pistons, or when less power 
is required, to use the steam more economically by 
working it expansively, which latter is accomplished 
with the present appliances by changing the travel of 
the valve. 

Question 184. How is the valve gear constructed so 
as to run the engine either backward or forward ? 

Answer. As already explained, in answer to ques- 
tion 76, two eccentrics are provided for each cylinder. 
These are set so that one of each pair will run the lo- 
comotive in one direction, and the other two the re- 
verse way. 



182 Catechism of the Locomotive. 

Question 185. How must the eccentrics for each cyl- 
inder be set in order that the one may run the engine for- 
ward and the other backward ? 

Answer. This can be best explained by reference 
to fig. 100, in which the piston, P, is represented 
at the beginning of the backward stroke, and the 
valve V has the requisite lead and is just about to 
open the front steam-port. It is obvious that, in 
order to complete the backward stroke of the pis- 
ton, the front port must be opened to admit steam 
into the front end of the cylinder, and therefore the 
valve must be moved in the direction indicated by the 
dart a. To do this, the upper arm of the rocker r must 
move in the same direction, and the lower arm must be 
moved the reverse way, as indicated by the dart e. If 
the crank is intended to move in the direction indi- 
cated by the dart N 9 then the centre of the eccentric 
must be above the centre of the shaft or axle, in order 
to move the rocker in the direction indicated by the 
dart e. Supposing, however, it was intended to move 
the crank the reverse direction, as shown by the dart 
N in fig. 101 ; it is evident in that case that the valve 
must be moved in the same direction as before, in 
order to open the front steam-port and thus admit 
steam to force the piston back. But if the crank 
turns in the direction shown by the dart JVJ fig. 101, 
then the centre of the eccentric must be placed below 
the centre of the axle in order to move the lower 
rocker arm in the direction of the dart e and the valve 
in that indicated by a. It will thus be seen that the 
centres of the eccentric for running forward and that 
of the one for running backward must be placed, the 
one above and the other below the centre of the axle 




Scale % in.=l foot. 



184 Catechism of the Locomotive, 

at the beginning of the stroke of the piston, as shown 
in figure 101. 

Question 186. Why is it that the centres of the eccen- 
trics are not placed opposite to each other on the axle ? 

Answer. Because before the beginning of the stroke 
of the piston it is necessary to move the valve from 
its middle position a distance equal to the lap before 
the steam-port begins to open. If we have a valve 
like that shown in fig. 10 — that is, without any 
lap — the centres of the eccentrics could be placed at 
right angles, or, as mechanics say, "square" with the 
crank, as was shown in fig. 11, and exactly opposite 
to each other, because such a valve begins to take 
steam as soon as it moves from the middle of the 
valve-face. If, however, we have a valve like that 
shown in fig. 27, it is plain that before it will admit 
or take steam, as it is called, in either of the steam- 
ports, it must be moved from the centre of the valve- 
face, or its middle position, a distance equal to the lap, 
L. For this reason, therefore, the eccentric, instead 
of being placed at half-throw* as it is called, must be 
so far ahead of the middle position as to have moved 
the valve a distance equal to the lap, and if any lead 
is given to the valve, equal to the lap and lead to- 
gether. In figs. 100 and 101, f g is a vertical line at 
right angles to the crank at the beginning of the 
stroke. It will be seen that the centre of each of the 
eccentrics is set far enough ahead of this line to give 
the valve the required lead. When the piston reaches 
the back end of the cylinder, the two eccentrics will 
occupy the position shown in fig. 102, in which posi- 



*This would be at right angles to the crank when the piston is at the 
end of the stroke. 



The Valve- Gear. 185 

tion the lower one would move the valve so as to turn 
the crank in the direction of the dart N, and the 
upper one in the reverse direction. It will he seen 
that in this position both of the eccentrics are again 
ahead of half-throw, when the piston is at that end of 
its stroke. 

Question 187. How is the motion of either eccentric 
communicated to the valve ? 

Answer. The ends of each pair of eccentric-rods 
are connected together by a link, a b, fig. 103. This 
link has a curved groove or slot, a b, in it, in which a 
block, B, fits accurately, so that it can slide freely 
from one end to the other. This block is attached to 
the lower rocker-arm by a pin, c, which works freely 
in the block. The two eccentric-rods G and D are 
attached to the ends of the link at e and/ by pins and 
knuckle-joints. It is apparent that if the link is 
down, or in the position shown in fig. 103 and also on 
a smaller scale in fig. 104, the motion of the upper 
eccentric-rod, which is usually used for the forward 
motion, will be imparted to the rocker, and thus to 
the valve, and when the link is in the position shown 
in fig. 105, that the valve will be moved by the lower 
or backward eccentric-rod B. In order to reverse the 
engine, it is then only necessary to provide the means 
of raising and lowering the links. This is done by a 
shaft, A, fig. 103, called a lifting-shaft, which has two 
horizontal arms, E^ one for each link, and a vertical 
arm, F. The links are suspended from the ends of 
the horizontal arms by rods or bars, g h, called link- 
hangers, which are connected to the links and to the 
arms above by pins, which enable the hangers to vi- 



Oniy one of these is shown in the engraving. 

16* 



The Valve- Gear. 



187 



brate freely. The lower pin is attached to a plate, 
L d, called a link-saddle, which is bolted to the link. 
The vertical arm of the lifting-shaft is connected by 
a rod, G G, called the reverse-rod, to a lever 0, 0, 
Plate II. in the cab called a reverse-lever, the construc- 
tion of which will be explained hereafter. This lever 
is worked by the locomotive runner, and by moving 
the upper end of it forward, the link will be lowered, 
and the rocker and valve will be moved by the forward 



|EyW£*J. B^BHR * 



Scale, % inch = 1 foot. 

eccentric ; and if the reverse-lever is moved back, the 
link will be raised, and the backward eccentric will 
move the valve. When this is done, the valve-gear is 
said to be thrown into the forward or backward motion, 
er forward or back gear. 

Question 188. Bow is the travel of the valve changed 
by the motion of the linkt 



188 



Catechism of the Locomotive. 



Answer. By either raising or lowering the link, so 
that the link-block and rocker-pin will be some dis- 
tance above or below the eccentric-rods. Thus in fig. 
104, the motion of the upper eccentric-rod, and in fig. 
105 that of the lower or back eccentric-rod is commu- 
nicated to the rocker-pin and the valve. If, however, 
the link should be raised so that the link-block and 
rocker-pin are somewhat below the upper or forward 




Scale, % inch = 1 foot. 

eccentric-rod, as shown in fig. 106, then the motion 
imparted to the rocker and valve will partake some- 
what of that of the upper and also of the lower ec- 
centric-rod. So long as the rocker-pin is above the 
centre of the link, the motion of the valve will partake 
most of that of the upper or forward rod, and the en- 
gine will then run forward, but when the rocker-pin 



The Valve- Gear. 189 

is below the centre of the link, its motion will be in- 
fluenced more by the back eccentric-rod, and the en- 
gine will then run backward. 

The motion of the link, which is somewhat complex 
and difficult to understand clearly, will perhaps be un- 
derstood better if we represent it in a number of suc- 
cessive positions of the whole stroke of the piston, as 
was done to show the motion of the eccentric in figs. 
11 to 24. We will therefore suppose that the link is 
in what is called full gear forward, as shown in figs. 
103 and 104. In fig. 108 the link is in the position 
it would occupy at the beginning of the stroke of the 
piston ; in fig. 109 it is in that which it will be in 
when the piston has moved four inches ; in fig. 110, 
when it has moved eight inches ; in fig. Ill, twelve ; 
and in figs. 112, 113 and 114, sixteen, twenty and 
twenty-four inches. Figs. 114 to 119 represent the 
successive positions of the link during the return 
stroke. In order to show the different positions of 
the link we have represented on a larger scale, in fig. 
120, the successive positions of the centre line of the 
link, which will indicate the motion imparted by it to 
the rocker. In order to designate each of these posi- 
tions, the centre lines in fig. 120 are numbered + and 
— 0, 4, 8, etc., etc., to correspond with similar num- 
bers in figs. 108 to 119. 

Thus the line -o -o, represents the position of the 
centre of the link which it occupies at the beginning of 
the stroke as shown in fig. 108. The line -4 -4, that 
represented by fig. 109, when the piston has moved 
4 in. The lines -8 -8, -12 -12, -16 -16, -20 -20, 24 
24, +4 -f4, etc., the successive positions of the centre 
of the link represented in figs. 108 to 119, The dot- 




Scale % in.= 1 foot. 




Scale A in- = * inch 




17 



Scale $ in. =l»nota. 



The Valve- G-ear. 19* 

ted lines h a and k b represent the two extreme po- 
sitions into which the rocker-arm would be moved by 
the action of the link. It will be seen that when the 
link is in the position shown, it imparts the full stroke 
of the eccentrics to the rocker-pin and consequently 
to the valve. We will now suppose that the link is 
raised up as shown in fig. 106, so that the position of 
the rocker-pin is just half-way between the end of the 
eccentric-rod and the centre of the link. This posi- 
tion is called half-gear. In fig. 121 the different 
positions of the centre line of the link and of the 
rocker have been laid out for half-gear in the same 
way as was done for full-gear before. From this it 
will be seen that the travel, a b, imparted to the rocker- 
pin and valve by the link when it is in the position 
shown, instead of being 5 in. is only 3J in. In fig. 
107 the link is raised up, so that the rocker-pin is in 
the centre of it or midway between the eccentrics. 
This position is called mid-gear. The successive posi- 
tions of the centre line of the link in this position 
have been laid down in fig. 122 in the same way as 
was done for full and half-gear. The movement of 
the rocker, it will be seen, is, for mid-gear, only 2\ in. 
These diagrams show that when the rocker-pin is op- 
posite the eccentric-rod, the valve receives the full 
throw of the eccentric, and that the motion imparted 
by the eccentric diminishes as the rocker-pin ap- 
proaches the centre of the link, so that, with eccen- 
trics having 5 in. throw and a valve with ■£ lap and \ 
in. lead, we can increase or diminish tbe travel of the 
valve from 2J to 5 in. by simply raising or lowering 
the link, which is done by the reverse-lever. 
Question 189. What i$ the effect of this variation of 



196 Catechism of the Locomotive. 

travel on the working of the valve and the admission and 
release of steam to and from the cylinder? 

Answer. It is almost precisely the same as that 
which is effected by increasing or diminishing the 
throw of the eccentric, which was explained in the 
answer to Question 52. In order to show this effect 
more clearly, we have represented by motion-curves,* 
fig. 123, the movement imparted to the valve by the 
Hnk when it is in full, half and mid-gear, as illus- 
trated in the preceding figures. The curve for full- 
gear is engraved in full heavy lines ; that for half-gear 
in lighter lines, and for mid-gear in dotted lines. 
From these curves it will be seen that when the valve 
is worked in full-gear the steam-port is opened wide 
at 2 in. of the stroke and steam cut off at 21 inches. 
When the valve is worked in half-gear the port is not 
at any time opened wide and steam is then cut off at 
17^ in. of the stroke, and when worked in mid-gear 
the greatest opening of the steam-port is no greater 
than the lead and the cut-off occurs at 4 inches of the 
stroke. 

It is of course possible to work the link in any in- 
termediate position between those which we have rep- 
resented. Usually the reverse-lever is arranged so 
that the steam will be cut off at 6, 8, 10, 12, 15, 18, 
and 20 inches of the stroke. 

Question 190. What is the greatest and the least 
admission of steam possible with the ordinary link mo- 
tion ? 

Answer. With 24 in. stroke of piston and 5 in. travel 
and -£• in. lap, steam can be admitted as shown by the mo- 
tion-curves during 21 in. or 87^- per cent, of the stroke, 
* The nature of these curves was explained in answer to Question 44. 



The Valve-Gear. 197 

and can be cut off at about 4 in. or 16f per cent. It 
will be seen, however, that in mid-gear the motion- 
curve becomes a straight line, and that the pre-admis- 
sion of steam, that is the admission of steam before the 
piston reaches the end of the stroke, is equal to that 
admitted after, so that it is impossible to work the lo- 
comotive with the link in that position. Practically 
it is found that no useful work can be done with a 
link if the steam is cut off at less than six inches, or 
one-fourth of the stroke. Even then the opening of 
the steam-ports is so small that the steam which en- 
ters the cylinders is very much wire-drawn. 

Question 191. How are the curves drawn which rep- 
resent the motion of the valve ? 

Answer. These motion-curves as produced by the link- 
motion are very difficult to draw, as the motion of the 
link is extremely complicated. It is doubtful, there- 
fore, whether those who have no knowledge of me- 
chanical drawing will be able to understand the fol- 
lowing description of the method of doing it, which 
we will try to make as clear as possible. 

In the first place, the centre S, fig. 124, of the axle, 
A, of the rocker, and B of the lifting-shaft, must be 
laid down in their proper positions. If, now, the valve 
has ■$■ in. lap and i lead, the lower rocker-pin must be 
one inch ahead of its middle position when the piston 
is at the front end of the cylinder, and at the begin- 
ning of the backward stroke. We will, therefore, 
mark the centre, a, of the rocker-pin in this position. 
If from the centre of the axle a circle, c d e, be drawn 
whose diameter is equal to the throw of the eccentrics, 
this circle will represent the path in which the cen- 
tres of the eccentrics will revolve. If, now, the dis- 
17*. 




Scale ^ in. =1. Incb.^ 







Scale % in. = 1 foot. 



200 Catechism of the Locomotive, 

tance from the centre of the axle to the centre of the 
lower rocker-pin, a, when the latter is in its middle 
position, he taken for a radius,* and from the position 
of the rocker-pin at the beginning of the stroke as a 
centre, the circle representing the path of the eccen- 
trics he intersected at two points, c and d, the 
points of intersection will represent the positions 
of the centres of the forward and backward eccen- 
trics. Having determined these positions, draw 
arcs of circles, f and g, from these centres with a ra- 
dius equal to the distance from the centres of the ec- 
centrics to the centres of the pins which connect the 
rods to the link. It is evident that at the beginning 
of the stroke the centres of the pins in the link must 
each be in one of these arcs. But the link is sus- 
pended by the hanger, % h, which oscillates from the 
end, t, of the lifting-arm, which for any one point of 
cut-off is stationary ; and therefore the point of sus- 
pension of the link must always be in the arc,y k, de- 
scribed from the centre of the pin, i, in the lifting- 
arm, with a radius equal to the length of the hanger. 
There are, therefore, three points in the link, each of 
which must be in one of the arcs which have been 
drawn, and which will determine the position of the 
link. This can be done easiest by drawing the link, 
X, fig. 125, on a stiff piece of paper, m n, and cutting 
off the back, p q, of it through the centres of the pins, 
s and t, and also cutting out a triangular piece, u, the 
apex of which will correspond with the centre of the 



* This is usually the radius of the link but in some cases either a 
longer or shorter radius is taken to draw the link. In the following ex- 
planation it is assumed that the link is drawn with this radius, or from 
the centre of the axle. Of course if a greater or lesser radius is used, due 
allowance must be made therefor. 



The Valve- Gear. 



201 



point of suspension, o. By placing this piece of paper 
on the drawing it can be moved, so that the three 
centre points, 5, t and 0, will respectively conform with 
the arcs, f g and j k, fig. 124. In this position the 
piece of paper will then be in the position of the link 
for the point of the stroke represented. By marking 
the centres of the link-pins on the arcs f and g, and 
from them as centres, with the length of the rods used 











nv j 
1 1 ' 1 r 

l| 1 j \Ja 




\ 1 M" v; 
1V \ 





Scale, % in.=l foot. 

to draw the arcs, two other arcs, v, w, be drawn inter- 
secting each other, the point d, where they intersect 
will be the centre from which the centre line of the 
link can be drawn with a radius, I d, equal to the dis- 
tance from the centre of the eccentrics to the centre of 
the link. This will give the first position -o -o, of 
the centre line of the link. As the rocker-pin muat 



202 Catechism of the Locomotive. 

always be in the centre of the link, it is obvious that 
the point at which the centre-line of the link inter- 
sects the arc in which the rocker-pin oscillates must 
be the position of the centre of the rocker-pin. With 
this determined the position of the valve can easily be 
located. 

In order to represent the link at any other point of 
the stroke, say after the piston has moved four inches, 
the position of the crank must first be laid down. To 
do this, allowance must be made for the irregularity 
due to the angularity of the connecting-rod, which 
was explained in answer to Question 54. From the 
centre of the axle, a circle, G D, whose diameter is 
equal to the stroke of the piston, is first drawn, which 
will represent the path of the crank-pin. A horizon- 
tal centre line, E F, should also be drawn through the 
centre of the axle and the centre of the cylinder. 
The intersection o of this line with the path of the 
crank-pin will be the position of the latter at the be- 
ginning of the stroke. If from this point a distance, 
o o, be laid off on the centre line equal to the length 
of the connecting-rod,* it will give the position of the 
wrist-pin at the beginning of the stroke, so that from 
this its successive positions for each inch of the stroke 
can be laid off. From its position after the piston has 
made say four inches of the stroke as a centre, and 
the length of the connecting-rod as a radius, if the 
path of the crank-pin be intersected at —4, the point 
of intersection will represent the position of the crank- 
pin at four inches of the stroke. The distance from 



* In order to get the engraving within the required limits, the diagram 
is drawn with a connecting-rod only h% instead of 7 feet. The latter is 
the length used in previous illustrations. 



The Valve- Gear. 



203 



to —4 is equal to 44 degrees of the whole circle. 
The eccentrics, being attached to the axle, of course 
move the same number of degrees that the crank does, 
and therefore, in order to determine their position 
when the crank has moved any distance, it is only nec- 
essary to move them as many degrees as the crank 
has. This can be done very easily by extending the 
radii of the eccentrics, when they are in the first posi- 
tion, until they intersect the path of the crank-pin at 
ef and d'. By stepping off from the latter points of 
intersection a distance d &" and d' d'", equal to o — 4, 
which the crank has moved, and then drawing other 
radii from the two points c'", d"', their intersection, 
c" d", with the path of the eccentrics will represent 
the position of the centres of the eccentrics when the 
crank is at —4. Having determined the position of 
the eccentrics, the link can be laid down as before, 
that is, from c" and d" as centres and with the length 
of the eccentric-rods as a radius arcs, f" and g", are 
drawn. Then with the paper template the positions 
of the centres of the link-pins in these arcs are deter- 
mined and marked, and from them with the length of 
the eccentric rods as a radius, two intersecting arcs, 
v", w" y are drawn, whose intersection gives the centre 
of the link from which its centre line, —4 —4, is 
drawn. This will give the position of the rocker-pin 
for another point of the stroke. In a similar manner 
its position can be determined for any number of 
points of the stroke, from which the position of the 
valve can easily be determined and laid down on the 
diagram for the motion-curve as was described in the 
answer to Question 44. Of course the valve will be 
moved from its middle position the same distance that 



204 Catechism of the Locomotive, 

the rocker-pin is,* only in an opposite direction. In 
order to lay down the position of the valve on the 
diagram for motion-curves, it is, therefore, only neces- 
sary to draw it in the same relative position as that of 
the rocker-pin which is given by the point of intersec- 
tion of the center line of the link with the path in 
which the rocker-pin oscillates. To construct the 
motion-curves it is necessary to determine the posi- 
tions of the valve for different points of the stroke 
and mark them on the horizontal lines which repre- 
sent the respective positions of the piston. Curves 
are then drawn through these points, either by hand 
or by constructing templates. The more points there 
are determined, the more accurate will be the curves. 
It is, therefore, best to lay down the position of the 
valve for each inch of the stroke of the piston. They 
should also be drawn full size, which of course was 
impossible for the illustrations which are given here- 
with. 

Question 192. Is there any other method of drawing 
these motion curves ? 

Answer. Yes: models which show the working of 
the valve-gear have been constructed with a pencil, to 
which the reciprocating motion of the valve is im- 
parted, and which traces a curve on a surface having 
the same motion as the piston. This method has 
been employed by the writer in an instrument which 
he has applied to the locomotive itself. The principle 
upon which it works will be understood by supposing 
that the steam and exhaust-ports as represented in the 
diagram for motion-curves, fig. 123, be drawn on a 

* This will be the case when the two arms of the rocker are of the 
same length, as they usually are. Sometimes, though rarely, they are 
>f ditlereiit lengths. 



Tlie Valve- Gear. 



205 



board, A B G D, fig. 126, but instead of standing ver- 
tical, as in fig. 123, they are represented in a horizon- 
tal position, and the board on which they are drawn 
is fastened to the cross-head Z, so that the former will 
move backward and forward simultaneously with the 
latter and the piston. A small shaft, F 9 is attached to 
suitable supports, j, which are fastened to the guides. 
This shaft has two arms, G and E, one vertical and the 
other horizontal and of the same length. The upper 
end of the vertical one, G, is then attached to the valve- 
stem or rocker-arm by a short connecting-rod, H, or 
other suitable means, so that the movement of the 
valve-stem will be imparted to the arm and shaft. 
Of course the end of the horizontal shaft then has ex- 
actly the same motion vertically that the valve-stem 
and valve have horizontally, with the very trifling in- 
accuracy due to the fact that the movement of the one 
is in a straight line, whereas the other is in the arc 
of a circle. 

Now if a pencil, P, is attached to the end of the 
horizontal arm, E, and is set so that its point indicates 
the exact position of the steam edge, h, of the valve, 
as shown in fig. 123, it is obvious that when the piston 
and board have moved four inches, the pencil will have 
moved downward and have drawn the portion of the 
motion-curve from h to i ; and when the piston has 
moved eight inches the curve will be drawn to^", and 
at 12, 16, 20 and 24 inches of the stroke the curve 
will be drawn to k, /, m and n. During the return 
stroke a corresponding curve, n o h, will, of course, be 
drawn. With such an instrument curves can be 
drawn for any position of the link, and they will show 
the exact movement of the valve during the whole 
18 



The Valve- Gear. 



207 



stroke, and will indicate all the defects resulting from 
bad proportions or construction, lost motion in the 
parts, or other causes of error or irregularity. 

In using this instrument, however, it is impracti- 
cable to attach a board to the inside of the cross-head, 
and it must therefore be fastened to the outside. The 
horizontal arm E should be made of thin steel, so as to 
form a spring. The end has a small boss* with a hole 
in it -j^- of an inch in diameter. This hole has a 
screw thread cut in it, into which an ordinary hard 
drawing pencil is screwed. The spring is so arranged 
that the pencil will not be in contact with the board 
unless it be pressed against it. The locomotive is 
then placed on a smooth piece of track with steam on 
and run very slowly, so that a person walking along- 
side can press the pencil against the surface of the 
board, which should be covered with drawing paper. 
By watching the cross-head when it reaches the end 
of the stroke, the pencil can then be pressed against 
the paper and kept in contact through the whole 
stroke and instantly released when the motion-curve 
is completed. The link can then be placed in another 
position, and thus any number of curves can be drawn, 
which will furnish the most accurate means of analyz- 
ing the motion of the valve. 

In practice it is best not to draw the lines which 
represent the edges of the ports, until after the curves 
are drawn and the paper removed from the board. A 
centre line must, however, be drawn on the engine from 
which to lay off the ports. This can be done by placing 
the valve in its middle position, and then fastening 



* The term "boss" is used to imply an enlargeme»t or increased 
thickness of any part. 



208 Catechism of the Locomotive. 

the shaft F in that position with a nut which should 
be provided for that purpose on the end of the shaft. 
After it is fastened in this position, detach the con- 
necting-rod H, and with one stroke of the piston a 
centre line can be drawn with the pencil P. From 
this centre line the edges of the ports can easily be 
laid off and drawn on the paper after it is taken off 
the engine. 

Question 193. Can the position of each edge of the 
valve, with any given amount of travel, be shown in its 
relation to the ports by one motion-curve, or is it necessary 
to draw such curves for each edge of the valve, as shown 
in fig . 28? 

Answer. One motion-curve is sufficient to represent 
the position of any part of the valve during the en- 
tire stroke. This will be apparent if it is remembered 
that each motion-curve is exactly like the others, as 
shown in fig. 28, the only difference being that the 
ports occupy different positions in relation to the 
curves. It is, therefore, only necessary to draw lines 
to represent the relative positions of the ports to the 
other curves to show the entire motion of the valve by 
one curve. To illustrate this it will be assumed that 
a motion-curve, h ij k I m n o p, and a centre line, a 
b, fig. 127, have been drawn with the instiument de- 
scribed in the answer to the previous question. The 
centre line a b, which will be equal in length to the 
stroke of the piston, should then be divided into 
inches, and lines ff 23 1, 22 2, etc., should be drawn 
through the points of division and at right angles to 
a b. If, now, we want to show the movement of the 
front steam edge of the valve in relation to the cor- 
responding steam port, a line, t, should be drawn per- 



The Valve- Gear. 209 

pendicular toff, to represent that edge of the valve 
at the beginning of the stroke. As it is impossible to 
determine accurately the position of this steam edge 
at the beginning of the stroke from the motion-curve, 
which is then tangent* to the line ff we must lay it 
off from the centre line, a b. This can readily be 
done if we remember that if a valve has -£ in. lap 
when it is in the middle position, as shown in fig. 27, 
and -vV in. lead at the beginning of the stroke, it must 
have moved if in. from the middle position at the be- 
ginning of the stroke as shown in fig. 28. The line 
t must therefore be drawn if in. from a b to represent 
its proper position in relation to the motion-curve, and 
as it has -fV in. lead, the steam edge, h h', of the steam- 
port must be drawn at that distance from t. Another 
line, m m', can then be drawn to represent the width 
of the front steam-port, e c'. From these lines the 
movement of the valve in relation to the front port, 
c c', and the admission of steam are shown as clearly 
as in fig. 28. 

If now we want to represent the motion and rela- 
tive position of the back steam edge of the valve in 
relation to its port, it is only necessary to assume that 
the line t represents that edge, and that the curve h i 
jklmn oh represents its motion, and to draw the 
back steam-port in its proper relation to it. When 
the valve is in its middle position, as shown in fig. 27, 
the outside edge of the port h is -£ in., or a distance 
equal to the lap, from the steam edge q of the valve. 
As the center line a b, fig. 127, represents the middle 
position of the edge of the valve, it is only necessary 

* A curve is said to be tangent to another curve or to a straight line 
when the two just touch, but do not intersect or cross each other. 

18* 




Scale jl inch— 1 



The Valve- Gear. 211 

to draw a line, n n', •£■ in., or the same distance from 
the centre line a b that the outer edge of the port d is 
from q in fig. 28, to represent this edge of the port in 
fig. 127, and another b V, at a distance from the for- 
mer equal to the width of the port, to represent its 
inner edge. A line, q, below the line 24, will repre- 
sent the edge of the valve at the beginning of the for- 
ward stroke. The curves in relation to the port d will 
then show the motion of the valve in relation to this 
port, in the same way that the dotted curve e?/does 
in fig. 28. 

If it is desired to represent the motion of the ex- 
haust edge h\ fig. 28, of the valve, it is only necessary 
to imagine that the line t, fig. 127, represents that 
edge, and then draw in the port d in the same rela- 
tion to it that it bears to the edge h' } in fig. 28. This 
has been done in dotted lines, c c' and e e', in fig. 127. 

If the reader will cut a paper section of a valve like 
that shown in fig. 27 and place the different edges, h, 
i, h' and q, so that they will successively correspond 
with the line t in fig. 127, the diagram will per- 
haps be more clear. If, for example, the paper sec- 
tion be placed to the right of the line t, so that the 
edge h will correspond with t, then it will be seen that 
the port c occupies the same relation to it that it does 
in fig. 28. If the valve be placed to the left, so that 
the edge q corresponds with t, then the port d will be 
in the same relation to it that it has in fig. 28. If 
the edges i and h 1 be made to correspond with t, then 
the ports drawn in dotted lines in fig. 127 will repre- 
sent the ports c and d in fig. 28. 

The position of the ports in relation to the centre 
line of the motion-curve can be determined, if it is 



212 Catechism of the Locomotive. 

kept in mind that the centre line a b, fig. 127, repre- 
sents the position of the different edges of the valve 
when the latter is in the middle of the valve-face as 
shown in fig. 27, and that the ports must he on the 
same side, and the same distance from the centre line 
that they are from the edge of the valve whose motion 
is represented. Thus if the movement of the steam 
edge h in relation to its port, c, was represented, the 
edge of the latter must be drawn on the motion dia- 
gram the same distance from the centre line that it is 
from h when the valve is in its middle position as 
shown in fig. 27. This distance is of course just equal 
to the lap of the valve. If the motion of the exhaust 
edge h f was represented in relation to the steam port 
d, then the inside edge of the latter would be drawn 
the same distance from the centre line a b in the dia- 
gram that the inner edge of the port is from the edge 
hf of the valve, which is equal to the inside lap. The 
exhaust port could also be drawn in the same way, but 
it would be liable to confuse a diagram made to so 
small a scale as that which has been employed for the 
accompanying illustrations, and it has therefore been 
omitted. Diagrams of this kind which are made full 
size will,. of course, show the movement of the valve 
more distinctly than is possible in the space occupied 
by the illustrations herewith. When they are made 
of full size, the lines indicating the ports should be 
drawn of different colors, so as to distinguish them 
from each other easily. Such diagrams will show the 
position of the valve in relation to the ports, and in- 
dicate the distribution of the steam during the whole 
stroke. It is only necessary to refer the curve to 
the proper line to determine the position of the valve 



The Valve-Gear* 213 

in relation to either of the ports for either the admis- 
sion or release of the steam. If, for example, we want 
to observe how the admission of steam is governed 
by the valve, by referring to fig. 127 we see that at 
the beginning of the backward stroke the valve has 
•fV inch lead; that at 1 J inches of the stroke the port 
c is wide open, as shown by the intersection of the 
motion-curve with the line m m' ; that the valve has 
received its maximum backward travel at 9 inches of 
the stroke, and begins to close the port at 15J inches, 
and completely closes it at 21 inches of the stroke. 
By referring the motion-curve to the lines n n' and b b', 
we see that the valve as shown by the line q at n' 
again has -fV inch lead at the beginning of the forward 
stroke ; that the steam port is wide open at If inches 
of the stroke ; begins to close at I65- inches, and is 
completely closed at 21 inches. By referring the 
curve to the lines e e / and c c' we see that the front port 
begins to open to the exhaust before the piston has 
completed its forward stroke and when it has nearly 
an inch to move, that it is wide open almost immedi- 
ately after the piston begins its stroke, does not begin 
to close until the piston has moved 19J inches of its 
stroke, and is completely closed at 23 inches of the stroke. 
By referring the curve to the lines ddf and##', almost 
the same phenomena will be observed for the forward 
stroke. In fact from such a diagram the whole motion of 
the valve can be studied and analyzed with the great- 
est accuracy; and, as has already been shown, the 
motion imparted to a slide valve by a link is of so 
complicated a nature that it is almost or quite impos- 
sible to observe its exact nature without such dia- 
grams. 



214 Catechism of the Locomotive, 

Question 194. Can a motion diagram be constructed 
to represent the motion of the valve with different amounts 
of travel ? 

Answer. Yes ; it is only necessary to construct mo- 
tion-curves for the same diagram for each distance 
traveled, and they will show the movement of the 
valve for the given amount of travel represented by 
the curves. This has been done in fig. 128, which is 
a reduced copy of a series of motion-curves taken from 
a locomotive. From this diagram the movement of a 
slide-valve worked by the link-motion can be seen 
from the highest to the lowest practicable point of cut- 
off. For convenience of reference the curves have been 
numbered. 

The smallest travel of the valve represented by 
curve No. 1 is a little less than 2\ in., and the ports 
are then opened only about -fc in., and the steam is 
cut off at 8 in. on the backward and 6| in. on the 
forward stroke. The exhaust is opened or the steam 
is released during the backward stroke at 17 in., and 
during the forward stroke at 16f . When the valve 
works with its greatest travel, as represented by curve 
8, it travels 5 in., and opens the steam port wide at 3 
in. of the backward stroke and 2\ in. of the forward 
stroke. The steam is cut off at 20f and 20J in., and 
its release takes place at 23^- in. of each stroke. The 
following table gives the greatest width of opening, 
the point of cut-off, the point of release, and the lead 
for each motion-curve on the diagram. This table 
has been made up from the motion-curves drawn with 
the instrument described in answer to Question 191, 
on a locomotive which had been running about eighteen 
months and whose valve-gear consequently was con- 




Scale ~i\ inch=l inoh. 



216 



Catechism of the Locomotive. 



siderably worn, as is indicated by the flatness of the 
motion-curves on each side at the point when the mo- 
tion of the valve was reversed. This flatness was 



f 

2, 


1-3 

1 

o 


Width of opening 
of steam-port. 


Point of cut-off. 


Point of release. 




>-l 
< 


Backwd 


Forwr'd 


Backwd 


Forw'rd 


Backwd Forw'rd 






< 
■ ? 


stroke. 


stroke. 


stroke. 


stroke. 


stroke. 


stroke. 






in. 


in. 


in. 


in. 


in. 


in. 


in. in. 


1 


H 


*i 


A 


8 


8f 


17 


16| A 


2 


n 


A 


H 


9* 


y* 


18ft 


18A : 


i 


3 


n 


A 


* 


12 


hi 


19j 


19A A 


4 


3* 


U 


» 


14 


14 


mi 


20A A 


5 


7 
8 


« 


16* 


16* 


21H 


21* A 


6 


4 


1* 


1A 


18± 


18* 


22g 


22J 


* 


7 


41 

*2 


H 


!} 


19ft 


19* 


22H 


22| A 


8 


5 


H 


20ft 


20* 


23* 


23* A 



caused by the lost motion in the valve-gear, the pencil 
remaining for a time stationary when the motion was 
reversed and while the parts were moving from their 
bearings on one side to those on the other. The 
curves and the table therefore show the operation not 
of a theoretically perfect valve-gear, but are examples 
of actual practice, with such imperfections as are in* 
cidental to ordinary locomotives. It will be seen that 
the instrument shows not only what the valve-gear 
should, but what it actually does do, and delineates 
all its imperfections. 

Question 195. What are the chief dimensions of the 
valve-gear represented in fig. 128 ? 

Answer. The throw of eccentrics was 5 in., the steam- 
ports were 1J in., and the exhaust-port 2| in. wide, 
the valve had j- in. outside and ^ inside lap and -^ in. 
lead at full stroke. 



The Valve- Gear. 217 

Question 196. What relation is there between the 
distance which the ports are opened by the valve, and its 
travel when worked by a link f 

Answer. As explained in the answer to Question 52, 
the width which the steam-ports are opened by the 
valve for the admission of steam diminishes with the 
travel of the valve. This is shown very clearly by 
the motion-curves, and also in the above table, from 
both of which it will be seen that when the valve 
travels only 2J- in. the steam-ports are opened only 
f% in. for the back stroke and -$? for the front. 
With 2f travel the opening is -fc and ||- in. With 
4 in. travel the port is opened 1J and 1 - 3 % in. and 
with 4J in. travel they would be opened wide. 
With 4J and 5 in. travel, as will be seen from the 
motion diagram, the ports are not only opened wide, 
but the valve throws " over " them, or travels beyond 
their inner edges. 

Question 197. How is the point of cut-off affected 
by the link ? 

Answer. Changing the travel of a valve with a link 
has a very similar effect to that produced by eccentrics 
of different throw — that is, the period of admission is 
increased with the throw of the eccentric and that for 
expansion lessened. This is shown clearly in both 
the motion diagram and the table. With the first 
curve and a travel of 2\ in. the steam is cut off at 8 
in. for the backward stroke and 6 j in. for the front, 
and with 5 in. travel steam is admitted during 20f in. 
of the backward and 20J in. of the forward stroke. 

Question 198. How is the point of release or exhaust 
of the steam affected by the link ? 

Answer. As the travel increases, it is delayed until 
19 



218 Catechism of the Locomotive. 

later in the stroke. Thus, with 2\ in. travel the 
steam is exhausted or released from the cylinder 
during the backward stroke when the piston has 
moved 17 in., and on the return stroke at 16f in., 
whereas, with 5 in. travel of the valve, the release is 
delayed until 23^ in. of the stroke. An examination 
of the diagram and table will show very clearly the 
relation of the point of release to the travel. 

Question 199. How is the lead affected by the ordi- 
nary link motion ? 

Answer. It is increased as the travel is diminished, 
as is shown in the table, and also by the inclination 
of the curves at the top and bottom of the diagram. 

Question 200. What is the cause of this change of 
the amount of lead? 

Answer. This can be best explained by reference to 
fig. 129, which represents a link with very short eccen- 
tric rods. If now the centre from which the link was 
drawn was in the centre of the axle S, and the eccen- 
tric straps embraced the axle instead of the eccentrics, 
their ends c and d would each describe the same arc, 
a b, parallel with the centre line, x y, of the link, and 
the latter could then obviously be raised and lowered 
without moving the rocker-pin at all. But the eccen- 
tric straps being attached to the eccentrics, as shown 
by the dotted lines, when the rods are raised or 
lowered they describe arcs, c e and g h, from the cen- 
tres s and t of the eccentrics, and not from the centre 
of the axle. When the link is raised then, the end 
of the upper rod obviously moves in the arc c e, and 
the top of the link is moved from the axle, as shown 
in fig. 130, a distance equal to the interval between 
the arc, a b, drawn from the centre of the axle, and 




Scale % in.=l foot. 



220 Catechism of the Locomotive. 

e f which the rod describes from the centre of its 
eccentric. When the link is lowered from back to 
mid-gear, a similar action takes place, as the end, d, 
fig. 130, of the lower rod describes an a,vc,fg, so that 
the whole link is thrown from the axle a distance 
equal to the space between the arcs described from the 
centre of the axle and the centres of the eccentrics. 
When the position of the eccentrics is reversed, as 
shown in fig. 131, the link is moved towards the axle, 
thus causing an increase of lead on the opposite side 
of the valve. We have employed for our illustrations 
very short eccentric rods, in order to make this action 
apparent by exaggerating it. It is obvious from the 
engravings that the difference in the lead is increased 
as the eccentric rods are shortened, and also as the 
distance between the points of connection of the rods 
with the link is increased. It will a 1 so be plain that 
increasing the throw of the eccentrics, that is, increas- 
ing the distance of the centres s, s, of the eccentrics 
from the centre S of the axle will also increase the 
variation in the lead in full and mid-gear. 

Question 201. What is meant by the distribution of 
steam in the cylinder ? 

Answer. It means the admission and exhaust of 
steam to and from the cylinder in relation to the 
stroke of the piston or the revolution of the crank. 

Question 202. What are the principal periods or ele- 
ments of the distribution of steam by the slide-valve and 
ink motion ? 

Answer. They are : 

1. The pre-admission or lead, that is, the admission 
of steam into the cylinders in front of the piston be- 
fore it has completed its stroke. 



The Valve- G-ear. 221 

2. The admission of steam after the piston has com- 
menced its stroke. 

3. The expansion of steam in the cylinder. 

4. The pre-release, or exhaust of steam before the 
piston has completed its stroke. 

5. The release, or exhaust during the return stroke 
of the piston. 

6. The compression of steam, or closing the exhaust 
before the piston has completed its return stroke. 

Question 203. What is meant by the clearance of the 
piston ? 

Answer. It is the space between the piston and the 
cylinder-head when the former is at the end of the 
stroke. If the piston touched the cylinder-head at the 
end of each stroke, it would cause a concussion or 
"thump" which would injure these parts. Owing to 
the impossibility of constructing machinery with abso- 
lute accuracy, it is therefore necessary to leave a space, 
usually from J to ^ in. wide, between the piston and 
the cylinder-heads, so as to be certain that they will 
not strike each other should there- be any slight inac- 
curacies in the length of the piston-rods, connecting- 
rods, frames or other parts. 

Question 204. Why is it desirable to open the steam- 
port and admit steam at the end of the cylinder towards 
which the piston is moving BEFORE the latter has com- 
pleted its stroke f 

Answer. Because it is essential, in order to insure 
a good action of the steam, that the maximum cylin- 
der pressure should be attained at the very commence- 
ment of the stroke. If the steam-port was not opened 
until after the piston had commenced its stroke, some 
appreciable time would be consumed in filling the 
19* 



222 Catechism of the Locomotive. 

clearance space and the steam-way with steam.* It is 
also found, especially if an engine is working at a 
high speed, that a slide-valve worked by the ordinary 
link-motion will not open the steam-port rapidly 
enough to enable steam of the maximum boiler pres- 
sure to fill the space after the receding piston, unless 
the valve begins to open the port before the piston 
reaches the end of its stroke. 

Another advantage resulting from the pre-admission 
of steam consists in the smooth working of the engine 
at high speeds, a circumstance which reduces greatly 
the wear and tear of the working gear. As the piston 
approaches the end of its stroke, the pre-admitted 
steam forms a kind of elastic cushion, which is well 
calculated to absorb the momentum of the recipro- 
cating parts at that instant. The pressure due to the 
momentum of these parts will, of course, depend upon 
their weight and the speed of working, increasing di- 
rectly as the square of the speed. It follows from 
this that the lead should increase with the speed, and 
that it should be greatest at high speeds. As has 
been shown before, this condition is fully accomplished 
by the ordinary shifting-link motion. 

Question 205. Upon what does the admission of 
steam into the cylinder depend ? 

Answer. It depends in the first place upon the open- 
ing of the throttle-valve, and the size of the pipes and 
passages through which it is conveyed from the boiler 
to the cylinder. In the second place, it depends upon 
the time and amount of opening of the steam-port by 
the valve. 



* The steam-ways are the passages which lead from the steam-chest 
to the cylinder, and are sometimes called steam-ports, but the term 
steam-wayg is used to distinguish the passages from their openings in 
the valve-seat, which latter are more properly called steam-ports. 



The Valve- dear. 



228 



Question 206. What should be the pressure of the 
steam in the cylinder during admission t 

Answer. In order that the steam may be used to 
most advantage, it should be admitted and maintained 
in the cylinder at full boiler pressure during the whole 
period of admission. If the opening of either the 
throttle-valve or the steam-ports is not sufficient to 
allow the steam to flow into the cylinder at full boiler 
pressure, the steam is said to be wire-drawn, and 
much of the advantage of using it expansively as has 
already been explained in answer to Question 59, is 
then lost. 

Question 207. Why is it difficult to admit and main- 
tain steam at the full boiler pressure in the cylinder during 
admission f 

Answer. Because it is necessary to reduce the travel 
of the slide-valve in order to cut off the steam " short," 
or soon after the beginning of the stroke of the piston. 
When the travel is reduced, the valve opens the port 
only a small distance, so that the area of the opening 
is not then sufficient to allow the steam to flow into the 
cylinder with sufficient rapidity to fill it at full boiler 
pressure, especially if the engine is working at a high 
speed. Thus, by referring to the table given on page 
216 and to the motion curves in fig. 128, it will be 
seen that when the steam is cut off at from £ to \ 
stroke, the port is opened for the admission of steam 
only from J to \ inch wide. From the curves it will 
also be seen that the valve then acquires its maximum 
travel and the steam-port its greatest width of open- 
ing very soon after the piston begins its stroke ; after 
which the port is gradually closed, so that before the 
steam is entirely cut ofl the opening is eo much re- 



224 Catechism of the Locomotive. 

duced in area that the steam cannot flow through 
it rapidly enough to maintain the steam at full boiler 
pressure in the cylinder when the engine is working 
at high speeds. 

Question 208. What means are used to overcome this 
difficulty and thus admit steam at full boiler pressure 
when the valve is cutting off short ? 

Answer. In the first place, the steam-ports are 
made from ten to twelve times as long as they are 
wide, so that a narrow opening will have a compara- 
tively large area. In the second place, by giving the 
valve lead, not only are the clearance space and the 
steam-way filled with steam when the piston begins its 
stroke, but the port is then open a distance equal to 
the lead. With the ordinary link motion, as has al- 
ready been shown, this lead increases as the travel 
and period of admission diminish, so that the smaller 
the total distance that the port is opened, the greater 
is its opening at the beginning of the stroke. As the 
steam is usually cut off short when locomotives run at 
high speeds, it will be seen that the increased lead 
which is imparted to the valve by the shifting link is 
an advantage rather than a disadvantage. But while 
it is often possible in this way to secure a pressure of 
steam in the cylinder at the beginning of the stroke 
equal or nearly so to that in the boiler, yet it is almost 
impossible to maintain this pressure during the whole 
period of admission, when the steam is cut off short 
and the engine working at a high speed. To obviate 
this evil what is called the Allen valve was designed, 
which is represented in fig. 132. This valve has a 
channel or supplementary port, a a, which passes over 
the exhaust cavity, and has two openings, b, b\ in the 



The Valve- G-ear, 



225 



valve-face. When the valve begins to admit or " take " 
steam at c, as shown in fig. 133, it will be seen that it 
also uncovers the opening b' at e and admits steam at 
b', which passes through the channel b* a a b and enters 
the steam-port e at b, and in this way there is a double 
opening for the admission of steam. The opening b 
of the supplementary port is closed as the valve ad- 
vances, but when this takes place the steam-port is 




Scale ^ in.=l inch. 

uncovered far enough to admit all the steam that is 
required. This form of valve is very efficient when 
the travel and point of cut-off are very short. It 
then gives just twice as much opening as the ordinary 
valve for the admission of steam. This improved 
valve has been much used in Europe ; but, although it 



226 Catechism of the Locomotive. 

is an American invention, has not received the atten- 
tion in this country which its merit deserves. 

Question 209. What is meant by the pre-release of 
steam ? 

Answer. It is the release of the steam before the 
piston has completed its stroke. If it is confined until 
the piston has reached the end of the cylinder, there 
will not be time nor will it be possible, with a slide 
valve and link-motion, to secure a sufiiciently large 
opening of the port to permit the steam to escape from 
the cylinder before the piston begins its return stroke. 
If there were no pre-release, there would therefore be 
more or less back pressure on the piston. 

Question 210. Upon what does the amount of pre- 
release depend. 

Answer. First, as has already been explained in an- 
swer to Question 51, on the amount of inside lap ; and 
second, on the outside lap of the valve and lead of the 
eccentrics ; and third, on the travel of the valve. The 
less the inside lap, the greater the outside lap and con- 
sequent lead of the eccentrics ; and the shorter the 
travel of the valve, the earlier will be the release. 
The proper amount of this pre-release depends upon 
the velocity of the piston and the quantity of steam 
to be discharged or the degree of expansion. From 
the motion-curves in fig. 128 it will be seen that it is 
a marked feature of the shifting-link motion that the 
pre-release occurs earlier in the stroke as the link ap- 
proaches mid-gear, or as the travel of the valve dimin- 
ishes. As the link is usually worked near that position 
when the engine is run at a high speed, it will be seen 
that in this respect again the link-motion is well 
adapted for working the slide-valves of looomotives. 



The Valve- Gear. 227 

Question 211. What governs the period of release. 

Answer. The release like pre-release is dependant 
upon the amount of inside lap, the outside lap and 
consequent lead of the eccentrics, and the travel of the 
valve. 

The addition of inside lap has the effect of closing 
the port earlier than it would be closed without, and 
thus shortening the period of release and also of re- 
ducing the area of the opening of the port. This will 
be apparent by referring to fig. 128, in which the valve 
had jfa in. lead. The dotted lines which represent 
the edges of the ports in relation to the exhaust edges 
of the valve are therefore drawn tV in. from the cen- 
tre line a b. If, however, there had been no inside 
lap, then the edges of the ports would have conformed 
to the line a b. It will be observed that the first curve 
crosses the dotted line g g / at 15^ in. of the forward 
stroke, which is the point at which the port is closed to 
the exhaust, or where the period of release ends and 
compression begins. If there had been no lap and the 
line g g / had therefore occupied the same position as 
a b, then the motion-curve would not have crossed it 
until the piston had reached 16 in. of its stroke, thus 
showing that the period of release had been lengthened 
and compression delayed. As the width of the open- 
ing of the port is represented by the distance of the 
motion-curve from the right hand side of the line g g/ 
which represents the edge of the port, it is obvious 
that if there had been no lap, so that the position of 
the line representing the edge of the port had occupied 
the position of a b, then the space between it and the 
motion-curve would have been greater, thus showing 
that the port would have been opened wider if there 



228 Catechism of the Locomotive. 

had been no inside lap. The width of the opening of 
the port to the exhaust is in fact always diminished 
by an amount equal to the inside lap. 

With the same travel, increase of outside lap and 
lead shortens the period of release, but has no effect 
on the width of the opening of the port to the ex- 
haust. 

Increase of travel, with the same outside lap, length- 
ens the period of release and also increases the width 
of the opening of the port to the exhaust. 

Question 212. What governs the period of compres- 
sion. 

Answer. As compression begins when release ends, 
or when the port is closed to the exhaust, it is con- 
trolled by exactly the same causes, and as the two 
events occur simultaneously, of course whatever short- 
ens the period of release lengthens that of compres- 
sion. 

Question 213. What effect do the clearance spaces 
and steam-ways have upon the compression of the confined 
steam ? 

Answer. By referring to the motion-curves in fig. 
128, it will be seen that the steam-port is closed by 
the exhaust edge of the valve, or compression begins 
some time before the piston reaches the end of the 
stroke. The result is that the remaining portion of 
the cylinder, through which the piston must move 
after the port is closed to the exhaust, is filled with 
steam of atmospheric pressure, or possibly a little 
above that pressure. As this is confined in the cylin- 
der, it is compressed by the advance of the piston. If 
there was no room between it and the cylinder at the 
end of the stroke, then either the cylinder would be 



The Valve- Gear. 229 

burs' or the valve would lift so as to allow the com- 
pressed steam to flow back into the steam-chest. The 
clearance and the steam-passages, however, afford con- 
siderable room, into which the confined steam can be 
compressed without danger of bursting the cylinder, 
or of raising the slide-valve when there is steam in 
the steam-chest. As the clearance spaces and steam- 
ways must be filled with high-pressure steam at the 
beginning of each stroke, it must be obtained either 
by taking a supply of " live "* steam from the boiler, 
or by compressing into the clearance spaces the low- 
pressure steam that still remained in the cylinder 
when the port was closed to the exhaust. By the lat- 
ter process, a certain quantity of steam is saved at the 
expense of increased back pressure. It should be 
borne in mind also that the total heat of the com- 
pressed steam increases with its pressure, and as this 
latter approaches that in the boiler, the temperature 
of the former must have been raised from that due 
to about atmospheric pressure to nearer the temper- 
ature of that in the boiler. These changes of temper- 
ature which the steam undergoes will affect the surface 
of the metal with which the steam is in contact during 
the period of compression ; it follows from this, that 
the ends of the cylinder principally comprising the 
clearance spaces must acquire a higher temperature 
than those parts where expansion only takes place. 
This is an important consideration, since the fresh 
steam from the boiler comes first in contact with these 
spaces, and by touching surfaces which have thus pre- 
viously been heated, as it were, by the high tempera- 



* The term " live " steam means steam taken direct from the boiler 
and which has not been used in the cylinder or to do any work. 

20 



230 Catechism of the Locomotive. 

ture of the compressed steam, less heat will be ab- 
stracted from the fresh steam, and therefore a less 
amount of water will be deposited in the cylinder.* 

It will thus be seen that the effect of compression is 
to fill the clearance spaces and steam-ways with com- 
pressed steam before pre-admission begins. As already 
stated, this is done at the expense of back pressure in 
the cylinder. It must be remembered that all the en- 
ergy, excepting that part which is wasted by loss of 
heat, friction, etc., which is consumed in compressing 
the confined steam, is again given out to the piston by 
expansion. The confined steam also acts as an elastic 
cushion to receive the piston, just as the steam which 
is admitted before the end of the stroke would if there 
were no compression. Compress on, therefore, has the 
effect of saving the quantity of live steam which it 
would otherwise be necessary to admit before the end 
of the stroke to fill the clearance spaces and steam- 
ways and also to " cushion " the piston. As already 
stated, the momentum of the piston and other parts 
depends upon their weight and the speed at which 
they are working, increasing directly as the square of 
the speed, from which it follows that the compression 
should increase rapidly with the speed, and should be 
the greatest at high speeds. As the ports are prema- 
turely closed to the exhaust with the shifting-link 
motion, and as the lead increases rapidly as the link 
approaches mid-gear, and the amount of compression 
is at the same time correspondingly augmented, it 
will be seen that the shifting-link motion fulfills these 
conditions very perfectly. 



* Bauschinger's Indicator Experiments on Locomotives, published to 
Vol. III. of the Bailroap Gazettes. 



The Valve- Gear. 231 

The pressure to which the confined steam will rise 
depends of course upon the amount of the period of 
compression, and also on the size of the clearance 
spaces. As it is possible to have such an amount of 
compression that it will exceed the boiler pressure, 
and thus raise the valve from its seat and be forced 
back into the steam-chest, some care must be exercised 
to proportion the one to the other, so that the degree 
of the confined steam may not be excessive. 

Question 214. How can the effect of the distribution 
of the steam upon its action in the cylinder be determined 
by experiment t 

Answer. As already explained in answer to Ques- 
tion 55, this can be done by an instrument called a 
steam indicator. 

Question 215. What is the construction of this in- 
strument ? 

Answer. The indicator now ordinarily used is the 
Richards indicator, the outside of which is represented 
in fig. 134 and a section in fig. 135. It consists of a 
cylinder, B, into which a piston, G, is accurately fitted, 
but so that it will move freely in the cylinder. The 
piston rod is surrounded with a spiral spring, D, the 
lower end of which is attached to the top of the piston, 
and the upper end to the cylinder cover. When 
steam is introduced below the piston it pushes it up in 
the cylinder and the spring is compressed. If there 
should be a vacuum below the piston, the air above it 
will press the piston downward and extend the spring. 
This latter occurs only when the indicator is used on 
condensing engines. Of course the distance which 
the piston is forced up by the steam pressure below it 
depends upon the amount of pressure and also on the 



282 



Catechism of the Locomotive, 



tension of the spring ; and therefore by attaching a 
pencil to the piston-rod so that it can mark on a 
moving card in front of it, a diagram will be drawn 
which would indicate the steam pressure, as was ex- 
plained in answer to Question 55. But there are 
some practical difficulties in the way of doing this. 

Fig. 134. Fig. 135. 




Scale 3 in.=l foot. 



It is found that if the pencil is attached directly to the 
piston-rod of the indicator, the distance through which 
they must move, in order to make the scale of the dia- 
gram sufficiently large to be clear, is so great that the 
momentum of the parts carries them further than the 
pressure of the steam alone would move them. The 



The Valve- Gear. 



233 



distance through which the pistons or instruments 
move, moreover, makes it impossible that the changes 
of pressure should be indicated simultaneously with 
the position of the piston ; the latter must travel while 
the action is taking place, and thus the diagram shows 
changes of pressure later or more gradually than they 
occur.* To overcome these and other difficulties, the 
piston-rod of the indicator which we have illustrated 
is attached at h to the short arm of a lever, F G, and 
to the end of the long arm a piece, F I, is attached, 
which carries a pencil, J. By this means the piston 
has only one-fourth of the motion that it imparts to 
the pencil, so that the momentum of the moving parts 
is comparatively slight. If the pencil was attached 
directly to the end of the lever, it is obvious that it 
would move in the arc of a circle, and that this would 
be a source of error in the diagram. To avoid this 
the pencil is attached to what is called a "parallel 
motion." This consists of a coupling-rod, F I, which 
connects the ends of two levers, F G and / H. The 
centre of the rod F I, to which the pencil is attached, 
will with this arrangement move in a straight line. 
The levers and all the parts are of course all made as 
light as possible, so that their weight will have little 
effect on the motion of the indicator piston. 

The paper or card on which the diagram is drawn 
is wrapped around a brass cylinder, A A. This cylin- 
der is made to revolve part of the way around by a 
strong twine, a b, which is wrapped around a pulley, b, 
at the bottom of the cylinder. The twine is attached 
to a lever, similar to that shown in fig. 30, which re- 
ceives a reciprocating motion from the piston of the 



* Richards' Steam Indieator, by Charles T. Porter. 

20* 



234 Catechism of the Locomotive 

engine. The twine can of course move the cylinder 
only in one direction, and therefore a coiled spring 
similar to a clock spring is placed inside of the cylin- 
der to draw it hack when the twine is relaxed. In 
this way the paper cylinder or drum receives a part of 
a revolution at each stroke of the piston, and moves 
simultaneously with it. This drum is used instead of 
a flat card, on account of the practical difficulties of 



Fig. 136. 
employing the latter. The motion of the paper on this 
drum will, however, be exactly the same in relation to 
the pencil as the motion of a flat card would be. 

The method of attaching an indicator to a locomo- 
tive is represented in fig. 136. It will be seen from 
this that it is placed over the center of the steam 
chest and connected to each end of the cylinder with 



The Valve- Gear. 235 

J-inch pipes. A globe valve was in the case repre- 
sented placed on each side of the indicator, so that it 
could be put into communication with either end of 
the cylinder, or could be completely shut off from both. 
A better plan, however, is to have a three-way cock at 
the point where the horizontal pipe connects with the 
vertical one leading to the indicator, as the passages 
in a three-way cock are more direct than those in 
globe valves. The arrangement of the levers for 
giving motion to the indicator drum, and of the seat, 
which is very requisite for the experimenter, will be 
readily understood from the engraving without further 
^explanation. It is thought by some engineers that 
the indicator should be applied as near to each end of 
the cylinder as possible. It is believed, however, 
that if the pipes, cocks, and their connections are made 
large enough so as not to impede the motion of the 
steam, no appreciable error will arise from the method 
illustrated in fig. 136. 

Question 216. What should be the form of an indi- 
tcator diagram, if the steam is distributed by a link motion 
so as to produce the best practicable action in the cylin- 
ders ? 

Answer. It should approximate to that shown in fig. 
136. In this diagram the vertical lines represent 
inches of the stroke, and the scale on the left the 
steam pressure in pounds per square inch. The at- 
mospheric and vacuum lines are also indicated, as al- 
ready explained in answer to Question 55. The points 
at which the different periods of the distribution be- 
gin are indicated by the letters a, b, c, d, e and/ These 
are in the order in which they occur : a, pre-admis- 
»ion; by admission; c, expansion; rf, pre-release; e, 



Catechism of the Locomotive. 



release ; and f, compression. The lines forming the 
outline of the diagram will be designated for conven- 
ience of description as follows : 

The line from a to b, the admission line. 

" « « h to e, the steam line. 

" " u c to d, the line or curve of expansion. 

" " " d to e, the exhaust line. 

" " " e to /, the line of back pressure. 

" " " /to a, the line or curve of compression. 




The diagram represents a distribution of steam pro- 
duced by a valve having J in. outside and -fa inside 
lap, and operated by the link motion represented in 
fig. 103. The eccentrics have 5 in. throw, and the 
steam-ports are 1J and the exhaust 2 j in. wide. The 
valve as shown by the diagram is cutting off at 8 in., 
or one- third of the stroke. Pre-admission begins when 
the piston still has ^ in. to move before reaching the 
end of its stroke. Admission of course begins with 
the stroke, expansion at 8 in., pre-release at 18£ in. ; 



The Valve- Gear. 



237 



release at the end of the stroke, and compression at 
17J in. of the return stroke. The valve is supposed 
to be set without any lead, or " line and line"* as it is 
called at full stroke. When the steam is cut off at 8 
in. of the stroke, the valve has 2f in. travel and $ in. 
lead. The steam pressure in the boiler is supposed to 
be 100 pounds above the atmosphere. Of course, when 
the valve cuts off at different points of the stroke, the 
periods of distribution will be somewhat changed ; but 
from the above diagram the principal features of a 
good distribution can be explained. 

These are : First, that the steam pressure should rise 
rapidly during the period of pre-admission, so that 
there will be full boiler pressure in the cylinder at the 
beginning of the stroke. When this occurs, the pre- 
admission line will rise from a to b, to such a point at 
b which will indicate full boiler pressure in the cylin- 
der. The same pressure should then be maintained 
in the cylinder during the whole period of admission, 
and the admission line from b to c should therefore be 
a straight horizontal line, as shown in fig. 136. When 
expansion begins, the pressure will fall, as was ex- 
plained in answer to Question 55. The expansion line 
should approximate a hyperbolic curve, but if there is 
much loss of heat by radiation or other causes, the 
diagram will fall considerably below the theoretical 
curve. With cylinders well protected and with dry 
steam the expansion line will fall slightly below a hy- 
perbolic curve at the beginning of the period of expan- 
sion, and rise above it during the latter part of the 
same period. The reason of this is that the cylinder 



* That is, the steam edges of the valve correspond with the 
edges of the port at the beginning of the stroke. 



238 Catechism of the Locomotive, 

is heated by the admission of live steam of compara- 
tively high pressure and temperature, so that, when 
the pressure becomes reduced by expansion, a part ot 
tho water which is condensed in the cylinder will be 
re-evaporated by the heat in the latter. From the 
point of the pre-release, d, to the end of the stroke, e, 
the exhaust line should fall rapidly, so that there will 
be no pressure behind the piston during its return 
stroke. To explain the theoretical form of the ex- 
haust line would lead us into a very abstruse discus- 
sion, which would be out of place here. It will be 
sufficient for our purpose to call attention to the fact 
that the pre-release should allow all the steam in the 
cylinder to escape before the piston reaches the end of 
the stroke, so that the back pressure during the re- 
turn stroke may be as low as possible. It is, however, 
only at comparatively slow speeds that the steam in 
locomotive cylinders escapes during the period of pre- 
release, so that the back pressure is reduced to that of 
the atmosphere. It is necessary in locomotives, as 
has already been explained, to contract the area of 
the blast orifices or exhaust nozzles, in order to stim- 
ulate the draft through the fire, so that the steam 
cannot escape with sufficient rapidity to reduce the 
back pressure to that of the atmosphere if the engine 
is running fast. Of course every pound of back pres- 
sure on the piston is so much loss of energy, and a 
reduction of the amount of work done by the engine j 
but it is a sacrifice which must be made in order to be 
able to generate the requisite quantity of steam. In 
studying the distribution of steam, however, every 
effort should be made to reduce the back pressure as 
much as is practicable, and yet maintain a sufficient sup- 



The Valve- Gear. 239 

ply of steam, and therefore the line of back pressure 
should conform as closely as possible to the atmos- 
pheric line. The compression line should be a hyper- 
bolic curve, beginning with the period of compression. 
In calculating both the compression and expansion, 
allowance must be made for the clearance space and 
steam-way. In a cylinder like that illustrated in fig. 
92, their contents would be about equal to that of two 
inches of the cylinder. Therefore, when steam is cut 
off at 8 in. of the stroke, instead of having a quantity 
of steam which will fill a cylinder 16 in. diameter and 
8 in. long, we have as much as would fill a cylinder of 
that diameter and 10 in. long. The same thing is 
true of the compression. This must occur in the above 
example when the piston has 6^ in. more to move be- 
fore completing its stroke. There is therefore a quan- 
tity of steam in front of it sufficient to fill a cylinder 
8^ in. in diameter. This steam is of course compressed 
by the advance of the piston, and if its pressure when 
compression begins is the same as that of the atmos- 
phere, then it will be 0.9 lbs. above it when the piston 
has only 6 in. to move and 3.2, 6.2, 10.5, 16.9, and 
27.5 lbs. effective pressure when the piston has 5, 4, 
3, 2 and 1 inches to move respectively, and when pre- 
admission begins, the pressure will have risen to 48.7 
lbs. If the back pressure is above that of the atmos- 
phere, of course the compression will be correspond- 
ingly increased. It will also be seen that, without any 
or with very little clearance space, the compression 
would at the end of each stroke rise above the boiler 
pressure. It being a peculiarity of the ordinary shift- 
ing-link motion that as the period of admission is re- 
duced that of compression is lengthened, the latter 



240 



Catechism oj the Locomotive. 



becomes very excessive when the steam is cut off at 
less than one-third or one-fourth of the stroke. 

Question 217. In what respect would a diagram made 
by an indicator differ from the theoretical form represented 
in fig. 136? 

Answer. It would be drawn with less exactness ; 
that is, the corners instead of being sharply denned, 
as in fig. 136, would be more or less rounded, as in fig. 
137, and the curves and straight lines would vary 




somewhat from the exact mathematical form indicated 
in fig. 136. The higher the speed at which the en- 
gine is working when the diagrams are taken, the 
greater will be the variation from the theoretical form. 

Question 218. If the amount of pre-admission is 
insufficient, how will it be shown in the indicator dia- 
gram f 

Answer. The effect of too little pre-admission is to 
lower the pressure of the steam at the beginning of 
the stroke, and at high speeds there will not be time 
enough nor sufficient opening of the steam-port to sup- 
ply the deficiency after the stroke has commenced. 



The Valve- Gear. 



241 



The corner of the diagram at b will then be very much 
rounded, as shown in fig. 138. This is apt to be the 
case when steam is admitted during a considerable 
part of the stroke, as a shifting-link motion then gives 
less lead than when it is worked nearer mid-gear. If 
the steam is cut off short, then the pressure in the 
cylinder during admission is very much below boiler 
pressure, and is apt to fall rapidly after the commence- 
ment of the stroke, as shown in fig. 138. 



>mm sm 



Question 219. Jf the opening of the steam-ports dur- 
ing admission is too small, what will be the form of the 
diagram f 

Answer. The effect will be very much the same as 
that produced by too little pre-admission or lead; that 
is, the pressure in the cylinder will be much lower 
than in the boiler and will fall rapidly during the 
periods of admission, as shown in fig. 138. 

Question 220. What defects will be indicated by the 
expansion curve of indicator diagrams f 

Answer. If the cylinders are not well protected, and 
there is much loss of heat from radiation, there will 
21 



242 Catechism of the Locomotive. 

be a rapid fall of pressure during the period of expan- 
sion, which will be shown by the expansion curve fall- 
ing below the theoretical curve shown in fig. 136. If, 
on the contrary, the indicator curve is much above the 
theoretical curve, it may be caused by a leak in the 
valve. As steam is quite as likely to leak from the 
steam-port into the exhaust as from the steam-chest 
into the steam-port, a valve which is not tight may 
produce just the contrary effect upon the indicator 
diagram. As it is usually quite easy to detect a leak 
in the valve by other means, the use of the indicator 
for this purpose is unnecessary. Attention is called 
to it, however, to show the impossibility of getting 
results of any value with the indicator if the valves 
are not steam-tight. 

Question 221. What should be observed regarding the 
exhaust line of the indicator diagram ? 

Answer. The most important point to be observed 
is, whether the pressure at the end of the stroke is 
reduced as low as possible, as at high speeds it is usu- 
ally much more difficult to exhaust the steam from 
than to admit it into the cylinder. As already stated, 
the blast in the chimney makes it almost impossible 
to exhaust the steam to atmospheric pressure when 
the locomotive is running fast. If the steam is re- 
leased too late in the stroke, as already explained, 
there will not be time enough nor sufficient opening 
of the port to allow the confined steam to escape from 
the cylinder before the end of the stroke, and this will 
be indicated on the diagram by the space between the 
line of back pressure and the atmospheric line during 
the commencement of the return stroke, as shown ui 
fig. 138. 



The Valve- Gear. 



243 



QtrESTiON 222. What should be observed regarding the 
line of back pressure t 

Answer. The most important point is, that it should 
approximate as closely as possible to the atmospheric 
line, as all the back pressure not only diminishes the 
efficiency of the engine, but is a total loss of energy. 
Too much inside lap will increase the amount of back 
pressure, but generally it is more influenced by the 
area of the blast orifices than by any other cause. 
Every effort should be made, therefore, to have them 
as large as possible and yet have the boiler make as 
much steam as is needed. 

When only one blast orifice is used for both cylin- 
ders, it often happens that when the rteam is » ex- 
hausted from the one cylinder it " blows " over into the 
other, and thus produces an additional amount of back 
pressure. This is shown by a rise or " hump " in the 
line of back pressure, as indicated in fig. 138. 

Question 223. Can the amount of compression which 
is needed be determined by calculation ? 

Answer. Yes; but it involves more abstruse prin- 
ciples of mathematics than it is thought best to intro- 
duce here. Some of the reasons can, however, be 
given, which will make the subject clearer, and enable 
the reader, if he has sufficient knowledge of mathe- 
matics, to investigate the subject still further. 

In the first place it is a well-known fact that the 
motion of a piston in the cylinder of a steam engine 
is not a uniform one, but increases in speed from the 
beginning of the stroke to the middle, and diminishes 
in speed from the middle to the opposite end. The 
cause of this is that the crank revolves at a uniform 
speed during 'the entire revolution, but the piston 



244 Catechism of the Locomotive, 

moves much less at the beginning of the stroke, with 
a given amount of revolution of the crank, than it 
does at the middle. This is shown in fig. 140, in 
which A is a cylinder and B the piston and abed 
the path of the crank. Now while the crank moves 
from a to 1, or fa of a revolution, the piston has moved 
If in., or a distance equal to that from a to V or to the 
base of a perpendicular drawn from 1 to the centre 
line a c. While the crank moves from 1 to 2, or 
through the second twelfth of a revolution, the piston 
has moved from V to 2', or 4| in., or 2J in. further 
than during the first twelfth of the crank's revolution. 
During the third twelfth of the revolution the piston 
moves from 2' to 3', or 6 in., thus showing that it 
continues to increase in the distance moved during 
each period of the revolution of the crank until the 
latter has made a quarter revolution. The speed of 
the piston then begins to diminish until it reaches 
the end of the stroke. It is slightly affected by the 
angularity of the connecting-rod, as already explained, 
but for the present this is disregarded. It is obvious 
now that if the momentum, or actual energy stored 
up in the piston and other reciprocating parts after 
they have passed the middle of the stroke, added to 
the pressure behind the piston, is greater than the re- 
sistance offered by the crank, the motion of the latter 
will then be accelerated and thus conveyed to the 
moving engine and train. If, however, there is any 
momentum in the piston when it reaches the end of 
the stroke, evidently it can exert no power to cause 
the crank to revolve, but must be expended by pro- 
ducing a pressure on the crank -pin and thus on the 
axle-boxes. Not only will such a pressure not cause 




21* 



246 Catechism of the Locomotive. 

the cranK to revolve, but it will be more difficult to 
turn the crank with such a pressure against it than 
it would be without. The momentum of the piston 
and other reciprocating parts at the dead point there- 
fore creates a resistance to the movement of the crank 
instead of helping to turn it. It will also be observed 
that after the crank has moved slightly from the dead 
point, any pressure on the piston will exert very little 
force which will tend to turn the crank. In fact the 
nearer the piston is to the end of the stroke the greater 
is the proportion which the friction of the crank-pin 
and axle bears to the useful effect of the strain in 
causing the crank to turn. Calculation shows that 
for about three degrees on either side of the dead 
points the effect of pressure on the crank-pin is actu- 
ally to retard the engine. If now the piston reaches 
the end of the stroke with a certain amount of unex- 
pended momentum stored up in it, if this energy is 
expended by producing pressure on the crank, then it 
will not only be a waste of energy but a double waste 
by retarding the motion of the crank. If, however, 
this energy can be absorbed by compressing steam 
which will fill the clearance spaces, it will not only 
prevent the retarding effect referred to, but the en- 
ergy in the piston and other parts will be converted 
into steam pressure, which will be given out in useful 
work during the next stroke. It would, of course, be 
impossible to arrest the motion of the piston instantly, 
and therefore its momentum is gradually absorbed 
from the time compression begins until it reaches the 
end of the stroke. As the energy of a moving body 
is equal to its weight multiplied by the square of its 
speed, it is obvious that to overcome this a different 



The Valve- G-ear. 



247 



Amount of compression would be required for each 
speed, and also that it must be adjusted to the weight 
of the moving parts. Such exact adaptation is n6t 
practicable on locomotives, nor does the link motion 
enable us to alter the amount of compression with so 
much exactness : but the explanation shows the value 
of increasing the amount of compression with the 
speed, which fortunately the peculiarities of the shift- 
ing-link motion enable us to do without difficulty. 

Question 224. What cause produces the form of dia- 
gram represented by fig. 139? 




Answer. It is produced by excessive compression, 
which causes the pressure in the cylinder to rise above 
boiler pressure before pre-admission begins. As soon 
as the port is opened, part of the steam in the cylin- 
der flows back into the steam-chest, and thus the 
pressure is reduced, as shown by the diagram. 

Question 225. How can we determine whether the 
steam is distributed in the cylinders to the best advantage, 
and how can we discover the fauU t if there is one, in tht 
link motion % 



248 Catechism of the Locomotive, 

Antwer, The indicator will show the action of the 
steam iD the cylinder, and motion-curves drawn with 
the instrument described in answer to Question 192 
will show the exact movement of the valve. By com- 
paring the indicator diagram with the motion-curves, 
the one will show the defects in the other.* 

Question 226. To what extent can the movement of 
the valve be modified by alterations in the proportions of 
the link motion ? 

Answer. The motion of the valve is susceptible of 
an almost infinite number of changes, by different va- 
riations and combinations of proportions of the work- 
ing parts of the link motion. These changes are, 
however, limited by the general laws which govern the 
motion of eccentrics, and therefore cannot influence 
the motion of the valve beyond certain limits. Hardly 
any variation can be made either in the proportions or 
arrangement of the working parts which will not have 
some influence upon the movement of the valve. Aside 
from the proportions of the valve itself, which have 
already been discussed, the throw of the eccentrics, 
the length of the rods and of the link, the point of 
connection of the rods with the link, the point of 
suspension, the position of the lifting shaft, the length 
of the arms, the length and position of the rocker arms 
will each of them effect the distribution of steam. 
The number of combinations of all these different 
proportions is of course almost infinite, and therefore 
any full discussion of them will be impossible here. 

Question 227. What are the most important points 
which require attention in designing a link motion f 



• See description of Richards' Improved Steam Engine Indicator, with 
> for it* u*e, by Charles T. Perter, London. 



The Valve- &ear. 



249 



Answer. It should be proportioned so that— 

First, the lead and the period of admission should 
be the same for each end of the cylinder, for each 
point of cut-off, and, if possible, in back as well as 
forward gear. 

Second, the width of opening for both admission 
and exhaust should be as large as possible when steam 
is cut off short. 

Third, the exhaust or pre-release should occur early 
enough and be maintained long enough to reduce back- 
pressure as low as possible. 

Question 228. Bow can the lead and period of ad- 
mission be equalized? 

Answer. It is impossible to make the periods of ad- 
mission absolutely alike for every point of cut-off in 
both fore and back gear. It is therefore customary to 
disregard the back gear, as engines are worked but 
little with the link in that position. Even for forward 
gear the periods of admission cannot be made exactly 
alike for each end of the cylinder and for each point 
of cut-off, and therefore it is usual to make the periods 
of admission alike for half-gear forward, in which po- 
sition the link is worked most. 

The periods of admission for the front and back 
ends of the cylinder can be changed most in relation to 
each other by altering the position of the point of sus- 
pension on the link. This can be done either by 
moving this point up or down, or horizontally. Usually 
links are suspended from a point halfway between the 
points of connection of the eccentric-rods and from J 
to | in. back of the centre line of the slot in the link. 
A somewhat better distribution can be secured by 
suspending it about 3 in. above the centre, but the 



250 Catechism of the Locomotive. 

suspending link must then be made so short that it 
is subjected to very great strains by the motion of the 
link, and this evil is usually considered much greater 
than the advantage which is gained thereby in the 
more equal distribution. The point at which the 
upper end of the suspension link is hung also influ- 
ences the relative amount of admission front and back. 
This point, of course, varies as the end of the lifting 
arm is raised or lowered. In designing valve gear it 
is usually tested by a full-sized model, which will 
show the exact motion of all the parts. The best po- 
sition for the lifting shaft and the length of its arm 
can be determined perhaps most satisfactorily by 
placing the link in full gear forward, then moving the 
point of suspension of the upper end of the link-hanger 
horizontally so that the front and back admission will 
be alike, and then marking this position. The same 
process should then be repeated for half gear and for 
the shortest point of cut-off. If the position of the 
lifting shaft and the length of its arm are then so ar- 
ranged that the end of the latter will move through 
the three points which have been thus determined, 
the admission will be very nearly equal for each end 
of the cylinder. Usually, however, it is impossible to 
arrange the shaft and arm so that they will conform 
exactly to these conditions, and therefore an approxi- 
mation is made which will come as near as possible to 
what is required. It may be stated, however, that 
the lifting shaft should be kept as low as possible, 
so as not to interfere with the eccentric-rods. In 
some cases the shaft has been suspended from the 
boiler, so that the outside eccentric-rod would work 
past or over the end of the lifting shaft, thus allowing 



The Valve- Gear. 



251 



the latter to be located lower than would otherwise be 
possible. 

Question 229. Which parts of the link-motion have 
the greatest influence on the distribution of steam ? 

Answer. The lap of the valve and the throw of the 
eccentrics. The effect of any change of these upon 
the distribution is very similar to that produced if a 
single eccentric is used, which was explained in the 
answers to Questions 49, 50 and 52. 

Question 230. What is the effect upon the admission 
of increasing the throw of the eccentrics with the same 
lap? 




Answer. As already explained, the effect is to in- 
crease the period of admission, or in other words to cut 
off later in the stroke, and also to increase the width 
of the opening of the steam-port or the distance which 
the valve throws over the port. This has an important 
influence upon the admission, when the link-motion is 
used. 

Question 231. What is meant by the angular advance 
of the eccentrics? 

Answer. It is the angle which a line, e f fig. 141, 



'2o'2 Catechism of the Locomotive. 

drawn through the centre of the axle and the centre 
of the eccentric makes with a vertical line a b, when 
the crank is on one of the dead-points or centres. 
Thus in fig. 141 the crank A is represented on the 
front centre. In order to give the valve the necessary 
lead the eccentric must be moved ahead of the vertical 
line a b. The angle c which the line e f (drawn 
through the centre of g of the eccentric andj^of the 
axle) makes with the vertical line is called the angular 
advance. 

Question 232. What is meant by linear advance? 

Answer. By linear advance is meant the distance 
which the valve has moved from its middle position 
at the beginning of the stroke of the piston. This, 
when the two rocker arms are the same length, is the 
same as the distance of the centre of the eccentric g 
from the vertical line a b, fig. 141. 
. Question 233. Why does the cut-off occur earlier 
with an eccentric having a short throw than with one 
which gives more travel to the valve ? 

Answer. Because it is necessary to give the eccen- 
tric with the short throw more angular advance in 
order to give the valve the required lead. This is 
illustrated in fig. 112, in which a section of a valve, 
V, and ports c, g, and d, are represented. In order to 
simplify the diagram as much as possible the rocker is 
left out and the valve is supposed to be moved by the 
rod R direGtly from the centre a of the eccentric. 
*The effect of the angularity of the connecting rod 
and eccentric rod is also neglected. The circle a b ef 
represents the path of the centre of an eccentric 



*It will be seen that this causes the position of the centre of the eccen 
trie to be reversed. 



The Valve- Gear. 



253 



having 5 in. throw, and A i j the path of one having 
oh in. throw. In order to give the valve the required 
lead, which is supposed to be just line-and-line at 
the beginning of the stroke, the linear advance of the 
valve must be equal to the lap, or J in. If therefore 
we draw a line, p a, parallel to the vertical centre line, 
e k, and J in. from it, the intersection of p a at a and 
h with the paths of the eccentric will be the centres 
of the eccentrics. If through these centres and the 
centre of the circle, lines, o a and o p, be drawn, the 
angles which they make with the vertical e k will be 
the angular advance. It will be seen from these lines 
that in order to give the valve the required lead it is 
necessary to give the eccentric with the small travel 
more angular advance than is necessary for the one 
with the larger throw. It is obvious, too, that when 
the centre of the larger eccentric has reached the point 
b the valve will have received its greatest travel, and 
that when it reaches p the steam-port c will again be 
closed or the steam cut off. If the small eccentric is 
employed, the valve will then have its maximum travel 
when the centre h reaches s, and the port will be closed 
when it reaches i. By drawing lines, o p and o n, 
through * and p, it will be seen that from the begin- 
ning of the stroke until the steam is cut off, if the 
large eccentric is employed, it, and consequently the 
shaft and crank, must move over an angle measured 
by the arc q t p. If the small eccentric is used, it and 
the crank must move through an angle measured by 
the arc u t n. In other words, the crank must turn a 
considerably greater distance before steam i3 cut off 
with an eccentric having a large than with one hav- 
ing a small throw. 
22 




Scale $r to*- 1 iaeh » 



■ t 



The Valve- Gear. 



255 



It is also quite obvious from fig. 142 why the port 
is opened a shorter distance with a small than with a 
large eccentric. The distances o s and o b are equal 
to half the throws of the eccentrics, or If and 2\ in. 
The linear advance o r is in both cases § in., and there- 
fore after the port begins to open the valve will be 
moved by the small eccentric a distance which is equal 
to If— 8=| in-? and by the large one 2-^— J=lf in. 

Question 234. What is the effect on the admission oj 
giving an eccentric with a small throw the same angular 
advance as one with a large throw, and then reducing the 
lap of the valve so that the lead will be the same in both 
cases f 

Answer. The admission and the cut-off will then 
occur at the same points of the stroke, but the ports 
will not be opened so wide. This is illustrated in fig. 
143, in which the paths of two eccentrics having the 
same throw as those in fig. 142 are represented. The 
centre, a, of the larger eccentric is represented in the 
same position in fig. 143 as in fig. 142. If a line is 
drawn from the centre of the larger eccentric to that 
of the axle, and if the centre, h, of the smaller eccen- 
tric is located on the intersection of this line with the 
circle representing its path, then the smaller eccentric 
will have the same angular advance, but the linear 
advance measured by the distance o t will be only § 
in. If the valve have the same lap as in fig. 142, its 
steam edges at the beginning of the stroke, if the 
small eccentric is employed, will occupy the position 
represented by the dotted lines A and B. If these 
edges are cut off, as shown by the full lines and shad- 
ing, then the valve will have the same lead as in fig. 
142. It is obvious, too, that if the smaller eccen- 




Scale -i^ in.=l inch, 




22* 



Scale ^ in.=l foot. 



258 Catechism of the Locomotive, 

trie has the same angular advance it will reach the 
point v, at which, with the reduced lap, the steam will 
he cut off, at the same time that the centre, a, of the 
large eccentric will reach p, at which point it cuts off 
the steam with the valve having the large lap. There 
is, however, this difference in the distribution, that in 
the one case the valve opens the port a distance equal 
to t s, and in the other a distance equal to r b. As o 
t is equal to the linear advance of the small eccentric, 
or § in., and o s to half the throw of the eccentric, or 
If, t s is equal to If — |=1J- in. The distance r b, as 
shown above, is equal to 2\ — g=lf in., so that the 
effect produced upon the admission of using an eccen- 
tric with a small throw and corresponding amount of 
lap is, that the ports are not opened so wide as with 
an eccentric having a larger throw. 

Question 235. How do eccentrics with a short throw, 
and valves with a corresponding amount of lap, affect the 
admission with a link motion as compared with eccentrics 
having a larger amount of throw and greater lap of valve ? 
Answer. The chief difference is that the ports are 
not opened so wide for the same period of admission. 
Thus in fig. 144 is a series of motion-curves drawn 
with a model of a link motion like that illustrated in 
fig. 103. The eccentrics had 5 in. throw, and the 
valve J in. lap outside and ^q in. inside. Fig. 145 
represents a series of curves, drawn with the same ar- 
rangement of valve-gear, excepting that the eccentrics 
had 3J- in. throw and the valve ^ in. lap. In both 
cases the curves represent the motion of the valve 
when cutting off at the same point of the stroke. The 
following table will show the relative amount of open- 
ing of the port. 



1 



The Valve-Gear. 



259 



Point of Cut Off 


Width of Opening of Steani-J'oi t. 


Eccentric 5 in. throw. 


Eccentric 3^ in. throw. 


6 in. 

8 " 
10 " 
12 « 
15 « 
18 " 
21 " 


3 7 2 in « 
9 it 
32 

H" 
ft " 

1 " 

31 a 

3 2 

1 1 *« 
J 4 


A Lo- 
ft " 
ft" 

ft" 
■j « 

H " 
ift " 



* The valve throws over 1% in. at this point. 

It will be seen from this that the eccentric with 5 
in. throw gives a greater width of opening for every 
point of cut-off than the one with 3J in. throw. For 
the higher admissions this is not important, but when 
steam is cut off short it will be observed that the width 
of the opening is very small. At high speeds the 
small opening is a great disadvantage. 

Question 236. Has it been determined what amount 
of opening is required for given speeds of the piston f 

Answer. Not with any degree of accuracy. It is 
customary to make the area of the ports about one- 
tenth that of the piston. It is certain, however, that 
with steam-ports of this proportion an opening consid- 
erably less than their whole area is sufficient to main- 
tain steam at boiler pressure in the cylinders. One of 
the defects of the link motion is that the opening of 
the port is very small when the steam is cut off short. 
It is best, therefore, to secure the largest practicable 
opening of the ports for the lower points of cut-off. 

Question 237. What are the proportions of the valves 
and eccentrics used in the ordinary practice in th>'s coun- 
try? 



260 



Catechism of the Locomotive. 



Answer. The following report made by a committee 
of the Master Mechanics' Association will show the 
proportions used on thirty-five different railroads, and 
is a fair indication of the common practice. 



. i ■ . i .,.-■■ , ■ ■ J_ 


J 


5* 




P 


TABLE 
Showing thb amount of lap, lead and 


s 


1 

r 


• 



s. 

3* 


TRAVEL OF THE VALVES OF LOCOMOTIVES 






g 


USED OX 35 OF THE RAILROADS IN THE 


^ 




UNITED STATES AND CANADA. 






89 

< 


i 




in. 


in. ! in. 


in. 


For locomotives running express pass, trains 25 use.. 


% 


Vz 5 


1-10 


•( i< « « « « 6 " .. 


X 


1-16 4% 


K 


<( t( << <( << << A H 


IX 


X 


5 


A 


" " " accom. " V 20 " ., 


X 


% 


5 


" " •' " " " 10 " .. 


% 


1-16 5>s 


1-16 


«i << « << << << g .< 


% 


3-16|4K 


* 


« " " heavy freight " 19 " !! 


% 


1-1615 


1-10 


«• " " " " " 11 " .. 


% 


X \V/2 


1-16 


«< << << (( (i «« K i< 


X 


3-164% 


1-10 



Question 238. What should be the width of the 
bridge between the steam and exhaust ports ? 

Answer. It is usually made about the same thick- 
ness as the sides of the cylinder, in order to secure a 
good casting ; but sometimes it is necessary to make 
it wider, in order to prevent steam from escaping from 
the steam-chest into the exhaust, which is apt to be 
the case if a valve has little lap and a long travel. 

Question 239. What determines the width of the 
exhaust-port ? 

Answer. The throw of the valve. This will be clear 
if we refer to fig. 146, which represents a valve with a 
travel of 5^ in. It will be seen that when it is in the 
extreme position in which it is shown the width A 
of the opening of the exhaust-port is very small. If 
this opening is contracted too much it will of course 



The Valve- Gear. 



261 



interfere with the free escape of the exhaust steam. 
It is therefore best to make the exhaust-port so wide 
that with the greatest travel of the valve the width of 
its opening will be either quite or very nearly equal to 
the width of the steam-port. 

Question 240. Where is the reverse lever heated and 
how is it constructed? 

Answer. It is located on the foot-board* K! K', as 
shown in plate II. It consists of a lever 0, 0, with the 
fulcrum at the lower end. The reverse-rod V k, which 
connects the lever with the vertical arm k of the lift- 
ing-shaft, is attached above the fulcrum of the reverse 
lever. Pigs. 147 and 148 represent side and end 




Scale -fa in.=l foot. 

riews of the lever on an enlarged scale and with some 
of the details attached which are omitted on plate II. 
G, are two curved bars, which in this country are 
usually called quadrants, but in England are called 
(and more properly) sectors. These are placed on each 
side of the reverse-lever and are fastened to some por- 
tion of the engine. They have notches, n, n, n, cut in 



* The foot-board K r K f , plates 2 and 3, is a platform for the locomotive 
runner and fireman to stand on and is located at the back end of the 
engine. 



262 



Catechism of the Locomotive. 



them to receive the latch L, which slides in a clamp, H, 
and holds the reverse-lever in the notches in which it 
is placed. This latch is operated by a trigger, D, which 
is grasped by the locomotive runner when he takes 



E'f" 



3 




Fig. 148. 



Fig. 147. 
Scale % in.=l foot. 



hold of the handle A of the reverse-lever. The trigger 
works on a pin, E, as a fulcrum and is attached to the 
latch by a rod, r r. When the trigger is pressed up 



The Valve- G-ear. 



263 



against the handle, the latch is raised out of the 
notches by the rod r r, and is pressed into them again 
by the spring 5 when the trigger is released. F is a 
set-screw which presses against a gib, G, and is in- 
tended to keep the latch tight and prevent the reverse- 
lever from shaking. 

Question 241. How are the notches in the sector ar- 
ranged ? 

Answer. They are usually arranged so that the steam 
will be cut off at some full number of inches of the 
stroke when the reverse-lever is in each one of the 
notches. They are therefore located so that the steam 
will be cut off at 6, 9, 12, 15, 18 and 21 inches, or at 6, 
8, 10, 12, 15, 18 and 21 inches of the stroke. A notch 
is also placed so as to hold the link in mid-gear. In 
some cases as many notches as there is room for are 
put into the sectors. The latter seems to be much the 
best plan, as it gives more gradations in which the 
valve-gear can be worked, and it is a matter of no con- 
sequence whatever in the working of an engine whether 
the steam is cut off at some full or some fractional 
number of inches of the stroke. By referring to fig. 
144 it will be seen how very great the difference of the 
distribution of steam must be, as indicated by the 5th, 
6th and 7th motion-curves. 

Question 242. How long should the reverse-lever be? 

Answer. The lever should be sufficiently long so 
that in throwing the link from full gear forward to 
full gear backward the handle A will move not less 
than four times the distance that the link is moved. 
It is much better to give the end of the handle A five 
or even six times the motion of the link, as there will 
then be a much easier action in reversing the engine. 



264 Catechism of the Locomotive. 

This will also make it possible to use longer sectors, 
and give room for more notches. 

Question 243. What provision is made in the revers- 
ing gear for overcoming or neutralizing the weight of the 
link and other parts of the valve-gear ? 

Answer. Their weight is counterbalanced by the 
pressure of a spring of some kind. In fig. 103 the 
two volute springs enclosed in a case, H, are used for 
this purpose. These are compressed by the rod m, which 
is attached to a short arm I, on the reverse shaft A, 
when the link is lowered, and consequently the ten- 
sion of the spring resists the weight of the link when 
the latter is down or in forward gear. Different kinds 
of springs are used for this purpose and sometimes are 
attached to the reverse-lever instead of to the lifting- 
shaft. 

Question 244. What is meant by " setting " a slide- 
valve ? 

Answer. It is to fasten the eccentrics in the right 
position on the axle and to adjust the length of the 
eccentric-rods and valve-stem so that the valves will 
give the required distribution of steam. 

Question 245. How are the valves of a locomotive 
sea 

Answer. After the wheels, axles, main connecting- 
rods and valve-gear are connected together, put the 
rocker-arm in its middle position, and lengthen or 
shorten the valve-stem so that the valve will be in the 
centre of the valve-face. Then place the crank on 
the forward centre and the full part of the forward 
motion eccentric above and that of the backward mo- 
tion eccentric below the axle, and fasten them to the 
axle temporarily by tightening up the set-screws. 



The Valve- Gear. 265 

Then throw the link down until the block comes op- 
posite to the end of the eccentric-rod, and turn the 
wheels,* and at the same time, observe whether the 
travel of the valve is equal to the throw of the eccen- 
tric and also whether it travels equally on each side of 
the centre of the valve-face. If its travel is greater 
than the throw of the eccentric, raise the link up ; if 
less, lower it down until the two are just equal, and 
then mark the position for the notches on the sections 
or quadrants to receive the latch of the reverse-lever. 
If the valve does not travel equally on each side of the 
centre of the valve-face, either lengthen or shorten the 
eccentric-rod, as may be necessary. Repeat this opera- 
tion for the backward motion, by raising the link 
up until the block is opposite the end of the lower 
eccentric-rod. After having done this, go over the 
whole process again to see whether it is all correct. 
Now with the crank on the forward centre, and the 
link in full gear forward, loosen the set-screws in the 
forward eccentric, and move it around the axle so that 
the valve will have the required lead and then fasten 
it again. Now raise the link up into full back gear, 
and set the backward eccentric in the same way. Then 
turn the wheels so as to bring the crank on the back 
centre, and observe whether the lead is correct for the 
back end of the cylinder. If it is not, lengthen or 
shorten the valve-stem or eccentric-rod so as to make 
the lead alike at both ends, and if it is then too much 
or too little, it can be increased or diminished by 
moving the eccentrics on the axle. 

* This can be done by moving the engine on the track, or by raising 
it off its wheels, so that the latter can be turned without moving the 
former. In some shops a pair of rollers is put in the traok so that by 
placing the driving wheels on them they can be turned without any diffi- 
culty. 

23 



266 Catechism of the Locomotive. 

Great care must be taken in setting valves to be 
sure that the cranks are exactly on the centres or 
dead points, and it is impossible to set them in that 
position with sufficient accuracy from the motion of 
the piston or cross-head, and therefore the centres of 
the crank-pins should always be set so as to conform 
to a line drawn through the centre of the cylinder and 
the axle. When the cylinders are horizontal, it is oi 
course only necessary to place the cranks on a hori- 
zontal line drawn through the centre of the axle. 

When the valves are set it should also be noticed 
whether the axle-boxes (whose construction will be 
explained hereafter) are in the centre of the jaws, and 
if not they should be moved to the centre by driv- 
ing wooden wedges between them and the frames, 
either above or below, as may be required. The posi- 
tion of the boxes has a very material influence on the 
valve-gear. 

If it is intended to lay off the notches on the sectors 
so as to cut off steam at certain definite points of the 
stroke, these points should be laid off in the guides 
from the motion of the cross-head. The latter being 
placed in any of the required positions at which steam 
is to be cut off, the reverse-lever should then be moved 
so that the link will just close the admission port. 
The lever can then be clamped to the sectors, and the 
wheels turned so as to show whether its position is 
correct for each end of the stroke. As before stated 
it is impossible to get the ordinary link-motion to cut 
off at exactly the same points at both ends of the cyl- 
inder, but a very close approximation can be made by 
proportioning the different parts properly. As has 
already been stated, it is believed to be a much better 



The Valve- Gear. 267 

plan to put as many notches in the sectors as possible, 
than to locate them for certain definite points of the 
stroke. 

In setting the valves of locomotives, care must be 
taken to turn the wheels forward for the forward mo- 
tion and backward for the backward motion. 

After the valves are set the position of the eccen- 
trics on the shaft should be marked, so that in case 
they become loose on the road they can easily be set 
again. It is usual, too, to mark the position of the 
valves with centre-punch marks on the valve-stem and 
on the stuffing-box of the steam-chest, so that with a 
gauge made for the purpose the position of the valve 
can be determined without taking off the steam-chest 
cover. 

In some cases the eccentrics are keyed on, which is 
done after their position is determined by setting the 
valves. The ends of the set-screws which are used to 
fasten the eccentrics should be cup-shaped and case- 
hardened, so as to hold as securely as possible to the 
axle when they are screwed down. 



PART XII. 
THE RUNNING GEAR. 

Question 246. What is meant by the running gear of 
a locomotive ? 

Answer. It means those parts, such as the wheels, 
axles and frames, which carry the other parts of the 
engine. As the Germans express it, it is the "wagon" 
of the locomotive. 

Question 247. How may the wheels be classified? 

Answer. As driving and carrying or truck wheels. 

Question 248. What service must the driving wheels 
perform ? 

Answer. The driving wheels, as indicated by their 
name, " drive " or move the locomotive on the track, 
as was explained in answer to Questions 64, 65 and 
66. As their adhesion depends upon the pressure 
with which they bear upon the rails, they must carry 
either a part or the whole of the weight of the en- 
gine. 

Question 249. What proportion of the weight of or- 
dinary locomotives is usually carried on the driving 
wheels ? 

Answer. Eight-wheeled " American " locomotives, 
which are most commonly used in this country, have 
about two-thirds of their weight on the driving wheels. 

Question 250. What is meant by the " truck " of a 
locomotive t 



The Running- Gear. 269 

Answer. It means one or more pairs of wheels which 
are attached to a separate frame and to the locomotive 
by a flexible connection, so that the axles are not held 
rigidly at right angles to the main frame, but can as- 
sume positions which approximate to that of radii of 
the curves of the track. In plates I, II and III, E E 
are the truck wheels, V V the truck frame, sandy, plate 
II, and fig. 40, the centre-pin, around which the truck 
frame turns. 

Question 251. What set vice does the truck perform? 

Answer. It carries the weight of the front end of the 
locomotive, and also guides it into and around curves 
and switches* 

Question 252. How does it perform the latter service ? 

Answer. It does it very much in the same way as 
the front wheels of an ordinary wagon enable it to 
turn around corners; that is, the truck wheels being at-* 
tached to a separate frame, which is connected to the 
locomotive b} r a centre-pin, just as the front axle of 
an ordinary wagon is connected by the king-bolt, can 
turn. 

Question 253. Why are two pairs of wheels used on 
a locomotive instead of one, as on an ordinary wagon ? 

Answer. Because it is necessary to have one pair of 
wheels guide the other. In an ordinary wagon the 
front axle is guided by the pole or shafts. Nearly 
every one knows the difficulty of moving a wagon 
when the pole or shafts are removed, especially if it be 
pushed from behind. The movement of the front 
axle is then uncontrolled, and it is impossible to direct 
the motion of the vehicle. The same thing would oc- 



* A switch is a movable pair of rails, by which a locomotive is enabled 
to run from one track to another. 

23*. 



270 



Catechism of the Locomotive. 



cur with a locomotive if a single pair of wheels were 
used, and attached in the same way as the front axle 
of a wagon. Thus if a single pair of wheels were con- 







Scale, % incb=l foot. 

nected to a locomotive by a centre-pin, a, fig. 149, so 
that the axle would be free to move around this pin, 



The Running- G-ear. 



271 



then if one of the wheels should strike an obstruction, 
say a stone, s. fig. 150, there would be nothing to prevent 
the axle from being thrown into the position shown in 
fig. 150, and the wheels would be quite sure to leave 
the track. When two pairs of wheels are used and 
both axles attached to the same frame, which is con- 
nected to the engine by a centre-pin, s, fig. 151, be- 
tween the two axles, then the wheels in moving round the 
centre-pin must move around the centre s in arcs of 
circles, m n, m n, described from the centre s. These 
arcs, it will be observed, cross the rails. Now if the 
wheels should move in that direction, the flange of one 




of them would come in contact with the rail and pre- 
vent it from moving any farther. It is therefore 
evident that wheels arranged in that way can only 
move about the centre-pin as far as the curvature of 
the track will permit. Trucks are sometimes used 
with only one pair of wheels, but the centre-pin is 
then placed some distance behind the centre of the 
axle, or in the same relation to it that the centre * is 
to the axle a a' in fig. 151. It is evident that if the 
frame for such a truck turns around the centre-pin, 



The Running- G ear. 273 

the wheels must move across the track in the same 
way as represented hy the arcs m n, in fig. 151. The 
construction and operation of trucks with a single 
pair of wheels will be more fully explained hereafter. 

Question 254. Why will a locomotive run around 
curves easier if the front axles are attached to a truck 
frame which is connected to the locomotive by a flexible 
connection ? 

Answer. Because the truck axles can then assume 
positions which conform very nearly to the radii of the 
curves of the track, and it is well known that if two 
or more axles, each with a pair of wheels on it, are 
attached to a frame with their centre lines parallel 
with each other, as shown in fig. 152, they will roll in 
a straight line, but if the centre lines of the axles are 
inclined to each other, as shown in fig. 153, the ten- 
dency will be to roll in a curve, the radius of which 
will depend upon the degree of inclination of the axles 
to each other. In order to make the wheels in fig. 
152 roll on the curves a b and c d, it will be necessary 
to slide them laterally a distance equal to that be- 
tween the curves and the straight lines m o and p r, 
and as the length of the outside curve is greater than 
the inside one, if the wheels are fastened to the axles 
so they cannot turn on them and roll on the curves, 
either the wheels on the inside or those on the outside 
must slip a distance equal to the difference in the 
length of the two curves. Considerable force will 
therefore be required to overcome the resistance due 
to the combined lateral "and circumferential sliding 
of the wheels, so that more power will be needed to 
make them roll in a curve than is necessary to make 
them roll in a straight line. If, however, the axles 



274 Catechism of the Locomotive. 

are inclined to each other, then the wheels will nak 
urally roll on a curved path, and it will not be neces- 
sary to slide them sideways to make them con- 
form to such a path. But if the wheels are all at- 
tached to the axles so that those on the same axle 
cannot turn independently of each other and are all of 
the same diameter, then either the inside or the 
outside ones must slip, because the path in which 
the outside ones roll is longer than the inside curve, 
so that even if the axles are inclined to each other 
more power will be needed to roll the truck in a 
curved path than to roll the wheels shown in fig. 152 
in a straight line. It is, however, a fact that a cone 
or a portion of a cone like that shown in fig. 154 will 
of itself roll on a curve. It will do the same thing if 
the middle is cut away, as indicated by the dotted 
lines in fig. 154 and as shown in fig. 155. If now the 
wheels are made so that their peripheries* form por- 
tions of a cone and the axles are inclined to each other 
as shown in fig. 156, then there will be no slipping on 
the track, because the outside wheel, being larger in 
diameter than the inside one, advances further in one 
revolution than the latter does, and thus rolls on the 
longest path in the same time that the inside or 
smaller wheel does on the shorter one. When this is 
the case, such wheels will roll in a curve as easily as 
those in fig. 152 will in a straight line. The degree of 
inclination of the axles and of the sides of the cone 
must, however, vary with the radius of the curve. But 
if the axles are parallel to each other, and the wheels 
conical, as represented in fig. 157, they will not roll 



* The periphery te the eutside surfaoe on which the wheel rolls. This 
part of a wheel is usually oalled the " tread." 



276 Catechism of the Locomotive. 

either in a straight line or in a curve without great dif- 
ficulty, because if they roll in a straight line, the wheels 
on one side being larger in diameter than those on the 
other, either the larger or the smaller ones must slip on 
the path in which they roll. If they roll on a curve, 
then each pair of wheels has a tendency to roll in a 
curve independent of the other, and therefore the wheels 
must slip laterally if both pairs roll on the same track. 
Thus, suppose two pairs of wheels, a, a 1 , and b, V, fig. 
157, to be made conical and attached to a frame so that 
their axles are parallel to each other. Now each pair 
of such wheels will have a tendency to roll io circular 
paths, a' i, a h, and V k, bj, the centres of which are 
at m and n, or at the apices of the cones of which their 
peripheries form a part. If they are made to roll in 
circular paths, c d, ef, described from a point g, then 
each pair of wheels must slip laterally over the space 
between the paths a / i, a h, in which they would 
naturally roll and that in which they are made to roll. 
Thus the wheel a would slide laterally the distance 
between the curve a h and a f, and a' that between a' i 
and c d; b would slide from b j to b f and b' from h' h 
to b' d. It will thus be ceen that in order that two 
pairs of wheels may roll with equal ease in a straight 
line and in curves, the wheels in the one case must be 
of equal diameters and the axles parallel, and in the 
other case the wheels must be of unequal diameters 
and their axles be radial* to the curve. This is equally 
true of any number of pairs of wheels. If we have 
three, four, or any number of axles, with wheels all 
attached to the same frame, if their axles are parallel, 



* That is, that their centre lines incline towards each other, and if ex- 
tended far enough would meet at the centre of the cury«. 



The Running- G-eanr. 



277 



and the wheels of the same diameter, they will roll in 
a straight line ; but if their wheels are conical and 
their axles radial, they will roll in a curve. 

For the preceding reasons it is therefore sufficiently 
obvious that if a locomotive is to run on both straight 
and curved tracks, on the former the wheels should be 
of the same diameter and the axles parallel, and on the 
latter the wheels should be conical and the axles radial. 





Scale % in. =1 foot. 
Question 255. How are the wheels made so that in 
curves they will act as though they were of the conical form 
described and on a straight track all be of the same diam- 
eters ? 

Answer. The periphery or tread of each wheel is 
made conical, but of the same size as the other, and 
24 



278 Catechism of the Locomotive. 

with the small diameter of the cone outside, as shown 
in fig. 158. On a straight track if the position of the 
wheels on the rails is such that their two flanges are 
equally distant from the rails, as shown, then obvi- 
ously at the points of contact with the rails the wheels 
are of the same diameter. That is, a is equal to b. 
But in running on a curved track, if the wheels are of 
the same diameter, as has been shown, they will roll 
in a straight line and consequently towards the out- 
side of the curve. The flange c — supposing it to be at 
the outside of the curve — will therefore roll towards the 
rail, and consequently the outside wheel will rest on 
the rail at a point nearer the flange, as shown in fig. 
159, where the diameter a is larger, and the inside 
one further from the flange where the diameter- b is 
smaller than at a and b in fig. 158 ; and consequently 
the action of the wheels is the same as though their 
peripheries were made of the form shown in fig. 157. 

Question 256. How are the axles of locomotives made 
to assume a 'position radial to the curves in the track ? 

Answer. This is only done approximately, as the 
mechanical difficulties in the way of doing it perfectly 
are so great as to render it impracticable. By attach- 
ing the truck to the locomotive by a flexible connec- 
tion or centre-pin, s, as shown in fig. 160 (which rep- 
resents a plan of the wheels of an ordinary locomotive), 
it is plain that the truck axles ef and g h, instead of 
remaining parallel to the driving-axles a b and c d, 
will, by turning around the centre-pin, *, adjust them- 
selves to the curve so as to approximate as closely to 
radii as is possible for two axles which are held par- 
allel to each other. Of course the further apart they 
are the greater will be their divergence from the po- 



280 Catechism of the Locomotive. 

sition of radii, and whether the tread of the wheels be 
cylindrical or conical the further apart their axles are 
the greater will he the divergence of the paths in 
which they would naturally roll from that of any curve 
on which they must roll. Thus, if the axles were 
twice as far apart as they are represented in fig. 157, 
and in the position shown in the dotted lines I U and 
o o', the wheels, if they are conical, would then natu- 
rally roll in curves drawn from the centres p and q. 
If the wheels are cylindrical, they would roll in 
straight lines. In either case the divergence of their 
paths / s and I r from the curve of the track is greater 
than a h and a' i, the paths in which they would roll if 
their axles were nearer together. This divergence in- 
creases with the distance between the axles, and there- 
fore the lateral slip of the wheels must be in the same 
proportion. 

Question 257. Is the resistance to rolling diminished 
by placing the truck axles nearer together ? 

Answer. It is, within certain limits. The nearer 
each other they are placed, the closer will the centre-pin 
of the truck be to the centre of the axles. The closer 
it is to the centre of the axle, the greater is the ten- 
dency of the wheels to become " slewed," or to assume 
a diagonal position to the rails as represented in fig. 150, 
and thus increase the resistance and also the danger 
of running off the track. The increase of resistance 
from this cause, after the axles reach a certain dis- 
tance from each other, is greater than the decrease 
from a closer approximation to the position of radii. 
In ordinary locomotives it is necessary to place the 
truck wheels from 5 ft. 6 in. to 6 ft. apart, in order to 
get the cylinders between them in a horizontal posi- 



The Running- Gear. 281 

tion. This distance apart works very well in ordinary 
practice. 

Question 258. What is meant by flange friction t 
Answer. It is the friction of the flanges of the wheels 
against the head of the rails. Thus if two pairs of 
wheels, a, a', b, b', fig. 151, be placed on a curve and 
rolled in the direction of the dart, the wheel a will roll 
towards the outside of the curve until the flange comes 
in contact with the rail. As already explained, if two 
axles are parallel to each other, no matter whether the 
wheels are conical or cylindrical, they must slip later- 
ally in order to roll in a curved path. As the flange 
must follow the curve of the rail, it forces the wheel 
laterally and thus compels it to roll in the curved 
path into which the rail is bent. As the wheel offers 
considerable resistance to sliding there is a corres- 
ponding pressure of the flange against the rail, and 
consequently the revolutions of the wheel produce an 
abrasive action between the two. This action is ob- 
viously increased with the distance between the axles, 
because, as has been shown, the lateral slip of the 
wheels is then greater than when they are nearer to- 
gether. It is also obvious that if the wheels are par- 
allel with the rails there will be no abrasive action of 
the flanges, but that the greater the angle at which 
the wheels stand to the rails the harder will the flanges 
rub against the rails, and the greater will be the 
flange friction. With the aid of geometry it can very 
easily be proved that the farther apart two parallel 
axles are, the greater will be the angle of the wheels 
to the rails on a curved track, and, therefore, the 
greater will be their flange friction. It must, however, 
be remembered that if the wheels are so close together 
24* 



282 Catechism of the Locomotive. 

that they are liable to become " slewed," or assume a 
diagonal position across the rails, as shown in fig. 150, 
the angle at which the wheels would stand to the rails 
would thus be very much increased. It has therefore 
come to be a very generally recognized rule that the cen- 
tres of axles should never be placed nearer together 
than the distance between the rails. 

Question 259. Is the flange friction of all the wheels 
ef a truck the same on any given curve ? 

Answer. No ; of the front wheels obviously only the 
flange of the one on the outside of the curve comes in 
contact with the rail. As the centrifugal force of the 
engine presses the back pair of wheels towards the 
outside of the curve, the flange of the outside wheel 
alone comes in contact with the rail. But as this 
wheel is constantly rolling away from the rail, as 
shown by the dotted lines h g, fig. 151, obviously the 
friction of its flange is less than that of the front out- 
side wheel, which always rolls towards the rail. The 
flange of the back inside wheel is carried outwards by 
the centrifugal force and also by the tendency of the 
wheels to roll on their largest diameters on a curve, so 
that its flange will not touch the rail. 

Question 260. Can the axles of driving wheels assume 
positions radial to the track ? 

Answer. In ordinary engines they cannot. Various 
plans have been devised for the purpose of enabling 
them to do so, but it is only recently that they have 
met with any success. Some of these plans will 
be described hereafter. It is, however, of less impor- 
tance that the driving axles, when they are behind 
the centre of the locomotive, should assume position* 
radial to a curved track than that the front wheek 



The Running- Gear. 283 

should. This is illustrated by a common road wagon, 
as all know the ease with which such a vehicle can 
turn a corner if we run it with the front axle ahead, 
and the difficulty of doing so when the back axle is in 
front. In the case of a locomotive the reason for it is 
very much the same as that which makes the flange 
friction of the back wheels of a truck less than that of 
the front ones From fig. 160 it will be seen that the 
outside driving-wheels, when the engine is running 
with the truck in front, are rolling from the rail and 
not against it. As stated before, the centrifugal 
force of the engine when in motion has a ten- 
dency to throw the wheels towards the outside of 
the curve. It will also be noticed that the front 
driving axle is near the centre of that portion of the 
eurve which lies between the centre s of the truck and 
the centre k of the back axle. If it were in the mid- 
dle between them, it would be exactly radial to the 
curve ; being near the middle, it approximates closely 
to that position, and therefore the flange friction of 
its wheels is very slight. It will be noticed that if 
the flange of the back or trailing-wheel on the inside 
of the curve were not kept away from the rail it would 
roll toward and impinge against that rail. But it will 
be noticed that the flange of the front driving-wheel 
will come in contact with the inside rail before that 
on the back wheel can touch it. For this reason, and 
also on account of the effect of the centrifugal force 
exerted on the engine and the tendency of the wheels 
to roll on their largest diameters, the flange of the in- 
side back wheel is kept out of contact with the rail, 
and as the back wheel on the outside of the cvure 



284 Catechism of the Locomotive. 

rolls away from the rail there is very little friction of 
the flanges of the back driving-wheels. 

It will also be noticed from fig. 160, that if the ra- 
dius of the curve is very short, the bend of the rails 
between the back pair of driving-wheels and the cen- 
tre of the truck is so great that the inside rail will 
press hard against the flange of the front or main 
driving-wheel next that rail. This of course produces 
a great deal of friction, and if the curve is excessively 
short the flange will mount on top of the rail and the 
tread of the opposite wheel will fall off from its rail. 
For this reason the centre-pin of the truck is some- 
times arranged so that it can move laterally, that is 
cross-wise of the track. In fig. 160 the centre-pin is 
represented as having moved some distance from the 
actual centre of the truck, which is represented with 
dotted lines. The front wheels of locomotives are also 
sometimes made with wide "flat" tires, that is, tires 
without flanges, so that there will be no friction 
against the one rail and no danger of falling off the 
other. 

Another action also takes place which facilitates 
the motion of the driving-wheels of ordinary engines 
around curves. Every one knows how easy the direc- 
tion in which the front wheels of a common wagon 
can be controlled by taking hold of the end of the 
tongue or pole. With the leverage which it gives the 
wheels and axle can easily be directed wherever it is 
desired. A similar action takes place in an ordinary 
locomotive. The front driving-axles are guided by 
the truck, which is attached to the frame ten or twelve 
feet in front of the driving-axle, and thus the truck 
exerts a leverage to guide the movement of the 



The Running- Crear. 285 

driving-axles, just as a common wagon can be guided 
by the pole. 

If the locomotive is run backward, then none of 
these advantages exist, and the flange friction of the 
back driving-wheels is excessive. Engines such as 
construction locomotives, which run backward as much 
as forward, wear out the flanges of the back wheels 
very rapidly on crooked roads. 

Question 261. What is meant by the "spread'' of the 
wheels or axles ? 

Answer. It is the distance between the centres of 
two axles. 

Question 262. What is the " wheel-base " of a loco- 
motive f 

Answer. It is the distance between the centres of the 
front and back or trailing-wheels. On ordinary en- 
gines, such as that illustrated in plate I, it is the dis- 
tance from the centre of the front truck to the centre 
of the back driving-wheels. 

Question 263. Is the " coning " of the tread of the 
wheels of much practical importance f 

Answer. There is great difference of opinion regard- 
ing it, but even if its action is very beneficial, the ad- 
vantage is very soon lost, owing to the wear of the 
wheels. It is, therefore, believed that the advantage 
is more apparent in theory than in practice. 

Question 264. How are the driving-wheels of locomo- 
tives constructed? 

Answer. They are made of cast iron with wrought- 
iron or steel tires around the outside. Fig. 161 repre- 
sents a perspective view of a pair of locomotive wheels 
and axle. The central portion of the wheel, that is 
the hub, spokes and rim, are oast in one pieo*. TJsn- 



286 



Catechism of the Locomotive. 



ally the hub and the rim, and sometimes the spokes, 
are cast hollow. The central portion of the wheel, 
that is the . part which is made of cast iron, is called 
the wheel-centre. 




Question 265. Bow are the tires fastened on the 
wheel-centres ? 

Answer. The insides of the tires are usually turned 
out somewhat smaller than the outside of the wheel- 
oentre. The tire is then heated so that it will expand 



The Running- Gear. 



287 



enough to go on the centre. It is then cooled off, and 
the contraction of the metal binds it firmly around the 
cast iron part of the wheel. As an additional security 
bolts or set-screws, a, a, fig. 161, are screwed through 
the rim and into the tire to prevent it from slipping 
off in case it becomes loose. In some cases the wheel- 
centre and the inside of the tire are turned conical, 
and the tires are then put on cold »nd held on with 
hook-headed bolts, C, as shown in fig. 162, which is a 




Fig. 162. Scale 3 in.=l foot, 
section of the tire and the rim of the wheel. The 
wheel-centre is made largest on the inside. As the 
strain against the flange of the tire is inward, the 
cone of the wheel-centre resists this strain. If it was 
curved or tapered the reverse way, the strain would 
come on the bolts, and it would also be impossible to 
remove the tires without first taking the wheels off 
the axles. This method of putting on tires has the 
advantage that they can be removed quickly and with- 
out heating the tires.* 



* It is exclusively used on toe Baltimore and Ohio Railroad. 



288 Catechism of the Locomotive. 

Question 266. Are there any standard sizes for the 
inside diameters of tires ? 

Answer. Yes. To avoid the great inconvenience 
arising from the diversity in the inside diameters of tires, 
the American Bailway Master Mechanics' Association 
has recommended that the inside diameter of tires should 
he made 36, 40, 44, 50, 56 and 62 inches. The thick- 
ness for the first three sizes to he 3 in. and the last 
three 2\ in. 

Question 267. How are the driving-wheels fastened 
on the axles f 

Answer. The huhs are accurately cored out to re- 
ceive the axles, and the latter are turned off so as to 
fit the hole hored in the wheel. The axles are then 
forced into the wheel by a powerful pressure produced 
either with a hydraulic or screw press, made for the 
purpose. In order to prevent the strain upon the 
crank-pins from turning the wheels upon the axle, 
they are keyed fast with square keys driven into 
grooves cut in the axle and in the wheel to receive 
them. The ends of these keys are shown at b, fig. 
161. 

Question 268. How are the crank-pins made ? 

Answer. They are made of wrought iron or steel 
and accurately turned to the size required for the jour- 
nals for the connecting-rods. Fig. 164 represents one 
of the main crank-pins, and fig. 163 a hack pin for an 
American engine. The main pin has two journals, 
one, B, to which the main connecting-rod is attached, 
and the other, A, receiving the coupling-rod. The 
hack pin has only one journal, A, for the coupling-rod. 

Question 269. How are the crank-pins fastened to the 
wheels f 



The Running- Grear. 



289 



Answer. They are turned so as to fit accurately 
holes which are bored in the wheels, and are usually 
" straight " or cylindrical. The pins are then either 
driven in with blows from a heavy weight swung from 
the end of a rope, or else pressed in with a screw or hy- 
draulic press. Sometimes the holes are bored tapered 
or- conical and the pins turned to the same form. 
They are then ground in with emery and oil, so as to 
fit perfectly, and are secured by a large nut and key 
on the inside of the wheel. 



Mg.W3 




Scale 1 



1 foot. 



Question 270. What are the pieces A, A, fig. 161, be- 
tween the spokes of the wheel for f 

Answer. They are called counterbalance weights, and 
are put in the wheels to balance the weight of the 
25 



290 



Catechism of the Locomotive, 



crank-pins, connecting-rods and pistons. The princi- 
ple of their action will be explained hereafter. 

Question 271. On what part of the axle does the 
weight of the engine rest ? 

Answer. It rests on the driving-axle boxes L, fig. 161, 
which are placed just inside and close to the wheel. 

Question 272. What are the driving-axle boxes for 
and how are they made ? 

Answer. They are cast iron blocks, L, fig. 161, which 
embrace and rest on the axle. The part of the axle 
on which the box bears is called the journal. Each 
box has a brass bearing, c, fig. 1G5, which bears on top 




Fig. 165. 

of the journal and which is consequently exposed to 
the friction and wear. Fig. 165 is a perspective view 
of a driving-box, which shows what is called the oil- 
cellar, d. This is a receptacle underneath the axle 
which is filled with wool or cotton waste and saturated 
with oil for the purpose of lubricating the journal. 
The oil-cellar is held in its position by two bolts, f f 
which pass through it and the driving-box casting. 
By removing the bolts the oil-cellar can easily be re- 
moved and the box can then be taken off the axle. 



The Running- Gear. 



291 



Question 273. How are the truck wheels made ? 

Answer. They are made of cast iron, usually in one 
piece. Eigs. 166 and 167 represent sections of two 
forms of wheels used for cars. Those used for loco- 
motive trucks are similar to these, excepting that they 
are usually a little smaller in diameter. They are 
made with a disc or plate which unites the tire to the 
hub, and in some cases they have ribs cast in the in- 
side, as shown in the two figures. Some are made 
with single and others with double plates, as shown in 




Fig. 166. Fig. 167. 
Scale Y 2 in.=l foot. 

the engravings, and still others with spokes similar to 
the driving-wheels. The tread of the wheel is hard- 
ened by a process called chilling. This is done by 
pouring the melted cast iron into a mould of the form 
of the tread of the wheel. The mould is also made of 
cast iron, but being cold cools the melted iron very 
suddenly, and thus hardens it somewhat as steel is 
hardened when it is heated and plunged into cold 
water.* 



* It should be mentioned here that it is only oertain kinds of cast iron 
which will be hardened in this way, or will " chill," as it is called. The 
cause to which this chilling property is due is not known. 



292 Catechism of the Locomotive. 

Question 274. How are the boxes, journals and jour- 
nal-bearings of the truck-wheels made ? 

Answer. They are very similar to those for the driv- 
ing-wheels, their chief difference being that those for 
the truck-wheels are smaller than those for the driv- 
ing-wheels. 

Question 275. How are the frames for locomotives 
constructed ? 

Answer. The frames, H H H, plates I, II and III, 
are made of bars of wrought iron from 3 to 4 inches 
thick and about the same in width. They are usually 
made in two parts, the one at the back part of the en- 
gine, to which the driving-boxes and axles are at- 
tached, and the other at the front end, to which the 
cylinders are bolted. The back part, or main frame, 
as it is called, is represented in figs. 168 and 169, and 
consists of a top bar, H H, to which pieces, a, a', b, V, 
called frame-legs, are welded. Two of these form what 
is called a jaw, which receives the axle-box, as shown 
in fig. 169. To the bottom of each jaw a clamp, c, is 
bolted to hold the two legs together. The two legs, a 
and b', are united by a brace, d d, welded to the bot- 
tom of the legs. A brace, m, unites the back end of 
the frame with the leg b, and is welded to each. 

The front part of each frame consists of a single 
bar, e, which is bolted to the back end, as represented 
in figs. 168 and 169, which show the construction 
clearer than any description would. These front bars 
extend forward to the front end of the engine, and a 
heavy timber, called a bumper-timber, E E, plates I, II 
and III, extends across from one to the other and is 
bolted to each of them. This timber is intended to 
receive the shock or blow when the locomotive runs 




25* 



294 Catechism of the Locomotive, 

against any object, such as a car. The cow-catcher or 
pilot, S, is fastened to this timber. 

The front bar of the frames also has usually two 
lugs or projections forged on it, between which the 
cylinders are attached. The latter are securely held 
in their position by wedges, which are driven in be- 
tween the lugs and the cylinder castings. 

The frames, as already stated, are made of wrought 
iron and are accurately planed off over their whole 
surface. 

Question 276. Bow are the frames fastened to the 
boiler ? 

Answer. As already stated, they are fastened to the 
cylinders with wedges and bolts, and as the cylinders 
are bolted to the smoke-box the frames are thus rigidly 
attached to the front end of the boiler. In order to 
strengthen those portions of the frames which extend 
beyond the front of the smoke-box and to which the 
bumper-timber is attached, diagonal braces, r* r 7 , plates 
I, II and III are bolted both to the timber and to each 
of the frames at their lower ends. The upper ends are 
bolted to the smoke-box. Other braces, d', plate II, 
are also fastened to the frames and to the barrel of the 
boiler. The frames are fastened to the fire-box by 
clamps, I, 1, plate I, called expansion clamps. These 
clamps embrace the frames so that the latter can slide 
through the former longitudinally. There are also 
usually two diagonal braces not shown in plate II, the 
upper ends of which are fastened to the back end of 
the shell of the fire-box at about the level of the crown- 
sheet, and the lower ends to the back ends of the 
frames. There are also usually transverse braces at- 
tached to the lower part of the frames, thus uniting 



The Running- G-ear. 



295 



the two together. The guide-yokes, j j, plate I, are 
also usually bolted to the frames and to the boiler. In 
many cases one only is used, which extends across 
from one frame to the other and is fastened to the 
boiler. 

Question 277. Why are the frames attached to the 
shell of the fire-box so as to slide longitudinally through 
the fastenings f 

Answer. Because when the boiler becomes heated 
it expands, and if it could not move independent of 
the frames its expansion would create a great strain 
on both itself and the frames. The fastenings to the 
fire-box are therefore made so that the frames can 
move freely through them lengthwise, but in no other 
direction. 

Question 278. How much more will the boiler expand 
than the frames in getting up steam ? 

Answer. From J to -f^ of an inch. 

Question 279. Why is it necessary to support the 
engine on springs f 

Answer, ^Because, however well a road may be 
kept up, there will always be shocks in running over 
it ; these occur at the rail joints and especially when 
the ballasting of the ties is not quite perfect. These 
shocks affect the wheels first, and by them are trans- 
ferred through the axle-boxes to the frame, the engine 
and the boiler. The faster the locomotive runs, the 
more powerful do they become, and therefore the more 
destructive to the engine and road, and consequently 
the faster a locomotive has to run the more perfect 
should be the arrangement of the springs. 



•The above answer and much of the material referring to springs ha* 
been translated from " Die Schule des Locomotivfuhrers," by Mess*-?, 
J. Brosius and B. Koch. 



296 Catechism of the Locomotive? 

If we strike repeatedly with a hammer on a rail, 
the latter is soon destroyed, while it can bear without 
damage a much greater weight than the hammer 
lying quietly on it. The axles, axle-boxes and wheels 
strike like a hammer on the rails at each shock, while 
the shock of the rest of the parts of the engine first 
reaches and bends the springs, but on the rails has 
only the effect of a load greater than usual resting on 
them. Another comparison will make still plainer 
the lessening by the springs of the injurious effect 
which the weight of the boiler, etc., exercises on the 
rails. 

A light blow with a hammer on a pane of glass is 
sufficient to shatter it. If, however, on the pane of 
glass is laid some elastic substance, such as india- 
rubber, and we strike on that, the force of the blow 
or the weight of the hammer must be considerably 
increased before producing the above-named effect. 
If the locomotive boiler is put in place of the ham- 
mer, the springs in place of the india-rubber, and the 
rails in place of the glass, the comparison will agree 
with the case above. From this consideration it will 
be seen how important it is to make the weights of 
the axles, axle-boxes and wheels as light as possible. 

Question 280. How are the driving-axle boxes 
arranged so that the weight of the engine will rest on 
springs ? 

Answer. They are arranged so as to slide up and 
down in the jaws. Springs, B, B', fig. 169, are then 
placed over the axle-boxes and above the frames. 
These springs rest on fl -shaped saddles, G, G', which 
bear on the top of the axle-boxes. The framo are 
suspended to the ends of the springs by rods ui b»"i, 



The Running- Gear. 



297 



9 f > tfi ff> 9') called spring-hangers. As the boiler and 
most of the other parts of the engine are fastened to 
the frames, their weight is suspended on the ends of 
the springs, which, being flexible, yield to the weight 
which they bear. 

Question 281. How are the frames protected from 
the wear of the axle-boxes which results from their sliding 
up and down in the jaws ? 

Answer. The insides of the legs, a, a', b, b', are pro- 
tected with shoes or wedges, h, h, which are held sta- 
tionary, and the box slides against the faces of the 
shoes, thus wearing the shoe or wedge but not the 
frame. 

Question 282. Why are the shoes usually made wedge- 
shaped f 

Answer. They are made in that way so that when 
they become worn, by moving one or both of them up 
in the jaws, the space between them is narrowed and 
the lost motion is taken up. They are moved by the 
screws i, i. If the boxes should become loose from 
wear, it would cause the engine to thump at each rev- 
olution of the wheels or stroke of the piston. 

Question 283. How are tjie springs for the driving- 
wheels made '! 

Answer. They are made of steel plates which are 
placed one on top of the other. These plates are of 
different lengths, as shown at B, B, in fig. 169, and 
are from 3 to 4 in. wide and T \ to ^ thick. The 
length of the springs measured from the centre of one 
hanger to the centre of the other is usually about three 
feet. 

Question 284. What determines the amount which a 
spring will bend under a given load ? 



2ita 



Catechism of the Locomotive* 



Answer. The number of plates, their thickness, 
length and breadth, and of course the material of 
which they are made. This can be explained if we 
suppose we have a spring plate of a uniform thick- 
ness, h, and a triangular form, of which fig. 170 is a 
side view and 171 a plan, and that it is clamped fast 
at its base, b. It is a well known mechanical law 
that any material of this form and under these condi- 
tions will have a uniform strength through its whole 
length to support any load, P, suspended at its end, 
and also that it will bend or deflect in the form of an 
arc of a circle. 



Fi e :170 




Question 285. How are locomotive springs usually 
made? 

Answer. In locomotives the arrangement of springs 
is always such that they are either supported in the 
middle and moved at the two ends, or such that they 
are supported at the two ends and loaded in the mid- 
dle ; for our consideration it is indifferent which of the 
two kinds of springs is taken for the present illustra- 



The Running- dear. 



299 



tion. That shown in plan and elevation in figs. 172 
and 173, which is formed of a wide plate placed diag- 
onally, and which in reality consists of two such tri- 
angular pieces as were represented in fig. 171 united 
at their bases m m, and loaded at two opposite corners, 
e and/, would answer the requirements mentioned if 



Fig. 172 




«««««$%t>^y w>> 

Fig. 175 

Scale % in.=l foot. 



300 



Catechism of the Locomotive. 



the great breadth, m m, were not an obstacle. This 
breadth is obviated by cutting the spring into several 

strips, aa,bb,cc,dd, i, fig. 173, of equal width, 

and placing these not side by side, but one over the 
other, as shown in figs. 174 and 175. 

In order that the separate strips and layers of the 
spring so made, figs. 174 and 175, may not slip out of 
place, the strips a a, b b, etc., are made in one piece, 
and all the plates are inclosed with a strap, F, figs. 
176 and 177. The plates, instead of being cut from 







F 


• • •(•I* • • • mm 



Fig. 778. 

F 



Scale % in.=l foot. 

a piece like that represented in fig. 173, are, however, 
made out of steel of the proper width, and the ends, in- 
stead of being cut off pointed as represented, are some- 
times drawn out thinner on the ends, like the point of a 
chisel, or oftener still cut off straight, as shown in fig. 
177. 

In order to hold the plates together a band, F, is 
put around the middle. This is put on hot, and be- 
comes tight by contracting as it cools. The centre of 



The Running-Gear. 



301 



the spring has a hole drilled through it with a pin, s, 
fig. 178 (which shows a cross section of a spring), to 
prevent the plates from sliding endwise. The plates 
at each end usually have a depression, a, fig. 179 

Fig Aid. 
a 




Scale 6 in.=l foot. 

(which is a cross section of a plate on a larger scale 
than the preceding figure), made in them on one side, 
and a corresponding elevation, b, on the other. The 
elevation on one plate fits into the depression on the 
other, and thus prevents the plates from slipping side- 
ways. 

Question 286. How should springs be curved? 

Answer. Springs should be curved so that when 
they bear the greatest load which they must carry 
they will be straight. If they are curved too much 




Scale 



1 foot. 



they are subjected not only to a strain which bends 
the plates, but to one which has a tendency to com- 
press them endwise. Thus if a spring like that rep- 
resented in fig. 180 is bent into a half-circle, it is ob- 
26 



302 



Catechism of the Locomotive. 



vious that the strain at the ends has no tendency at 
all to bend the plates, but only to compress them end- 
wise. Near the middle the strain will of course bend the 
spring. In the one direction the spring is flexible and 
elastic, and in the other it is not ; and as the strain 
of compression depends on the amount of curvature, 
the greater the latter is, the less flexibility and elas= 
ticity the spring will have. 

Springs are often given a double curve, as shown in 
fig. 181. This is not to be recommended, because 
when a spring bends the plates must slide on each 
other. If they have but a single curve, they will 
do so and remain in contact through their whole 
length, but if they have two curves they will separate 
and therefore " gape," as it is called. 



Fig 181 




Scale % in.=l foot. 

Question 287. What is meant by the elasticity of a 
spring f 

Answer. It is the amount which a spring will deflect 
or bend under a given load without having its form 
permanently changed. If the bending is so great that 
the spring does not recover its original form when the 
load is removed, then the strain to which it is sub- 
jected is said to exceed the limits of elasticity, and if re- 
peated often it will ultimately break the spring. 

Question 288. What is meant by the elastic strength 
and the ultimate strength of a spring ? 

Answer. The elastic strength is the strain it will bear 



The Running- Gear. 303 

without being strained beyond the limits of elasticity, 
and the ultimate strength is the strain which will break 
it. 

Question 289. What determines the strength of a 
spring ? 

Answer. It depends of course (1) upon the material 
of which the spring is made ; (2) its strength increases 
in proportion to the number of plates, and (3) to their 
width, and (4) in proportion to the square of their 
thickness, and (5) as the length diminishes. 

Thus, if we wanted to double the strength of a 
spring like that shown in figs. 170 and 171, it could be 
done in either of the following ways : (1) by making 
it of material twice as strong ; (2) by putting another 
plate just like it on top ; (3) by doubling the width of 
the base b, which would make the strength of the 
whole plate twice what it was before ; (4) by making 
the whole plate about four-tenths thicker, which 
would increase its strength, as already stated, in pro- 
portion to the square of the thickness as 1.4x1.4=2 
nearly ; (5) by reducing the length to one-half what 
it is in fig. 170. 

Question 290. What determines the elasticity of a 
spring ? 

Answer. (1) The material of which it is made ; with 
the same material the elasticity increases (2) as the 
number, and (3) as the width of the plates diminishes, 
and (4) with the cube of the length, and (5) decreases 
with the cube of the thickness of plate. 

Thus, supposing the plate in figs. 170 and 171 to 
be § in. thick and the deflection d 2\ in. ; the latter 
would be only half as much or \\ in. (1) if it were 
made of material twice as stiff, or (2) with two such 



304 



Catechism of the Locomotive. 



plates, or (3)with one twice as wide at the base. If (4) 
the length were doubled, the deflection would be equal 
to 2x2x2=8 times what it was before, or in propor- 
tion to the cube of the length. If (5) the thickness 
wer^ doubled the deflection would be reduced in the 
same proportion, and would be only one-eighth of 2J 
in., or T % in. 

Question 291. What should be the proportion of the 
plates of a spring in relation to each other ? 

Answer. The lower plates should diminish regularly 
in their lengths. The reason for this will be apparent 
from the fact which has already been stated, that if a 

Fi 9 . m. 




Scale %m.=\ foot. 

triangular plate of uniform thickness is clamped fast 
at its base, it will, if loaded at the end, be of uniform 
strength throughout its whole length. It is immate- 
rial what the length of the base of such a triangle is, 
if the two sides are of equal length and the thickness 
of the plate is uniform, not only its strength but the 
amount of deflection or bending from any load will be 
equal all through its length. If, therefore, we make 
a spring by cutting a plate formed of two such trian- 
gular pieces united at their bases into strips, as has 
already been explained, evidently the spring made of 



The Running- Gear. 305 

them will have a uniform strength throughout its 
whole length. As the strips thus made diminish in 
length regularly, it is evident that if the spring 
plates are made of steel rolled of the requisite width, 
their length should be the same as that of those cut 
from the plate referred to above. When this is the 
case the lower outline, abba, fig. 183, of the spring 
will, when the spring is not bent, be straight lines. 
Sometimes the lower outline of springs is made curved, 
as shown in fig. 182. This gives too much strength 
near the strap F, and too little near the ends. In 
drawing springs, therefore, it is best to lay them out 
with the plates straight, as shown in figs. 182 and 183, 
and after determining the thickness, drawing a straight 
line from the strap to the end of the longest plate will 
give the best form of the spring and the length of each 
of the plates. It is necessary, however, to put a suf- 
ficient number of long plates in each spring to give it 
the required strength next to the attachment of the 
hanger. Sometimes one or more of these long plates 
are made heavier than the rest. The evil of this 
method of construction will be apparent if it is remem- 
bered that the greatest permissible deflection up to 
the breaking of the spring decreases with the cube of 
the thickness of the plate and its strength increases 
with the square of the thickness. Now if we have a 
spring with say ten plates § in. thick and one on top f 
in. thick, the thick plate will have a strength four 
times that of the thin plates, but its elasticity will be 
only one-eighth that of the thin plates, and therefore 
it will require eight times as much load to bend it any 
given distance as is needed to bend the thinner plates 
the same distance. But its strength is only four times 
26* 



306 Catechism of the Locomotive. 

that of the thin plates, so that for any given amount 
of elasticity the thick plate must bear twice as much 
load as it has strength to carry. This shows what a 
great mistake is committed if some of the plates are 
made thicker than others, a conclusion which is sup- 
ported by practical experience, as it is found that if 
the top plates are made thicker than others, the thick 
ones break most frequently, which is the necessary re- 
sult of the supposed strengthening by increasing the 
thickness of the top plates. 

Question 292. *How can we find by calculation the 
elasticity or deflection of a given steel spring ? 

Answer. By multiplying the breadth of the 

PLATES IN INCHES BY THE CUBE OF THE THICKNESS 
IN SIXTEENTHS, AND BY THE NUMBER OF PLATES : 
DIVIDE THE CUBE OF THE SPANJ IN INCHES BY THE 
PRODUCT SO FOUND, AND MULTIPLY BY 1.66. THE 
RESULT IS THE ELASTICITY IN SIXTEENTHS OF AN 
INCH PER TON OF LOAD. 

Question 293. How can we find the span due to a 
given elasticity and number and size of plates ? 

Answer. By multiplying the elasticity in six- 
teenths PER TON BY THE BREADTH OF PLATE IN 
INCHES, AND BY THE CUBE OF THE THICKNESS IN 
SIXTEENTHS, AND BY THE NUMBER OF PLATES : DI- 
VIDE BY 1.66, AND FIND THE CUBE ROOT OF THE 
QUOTIENT. THE RESULT IS THE SPAN IN INCHES. 

Question 294. How can we find the number of plates 
due to a given elasticity, span, and size of plate ? 

Answer. By multiplying the cube of the span 



*The following rules for calculating the proportion and strength of 
steel springs are from Clark's Railway Machinery. 

t The span is the distance between the centres of the spring-hangers 
when the spring is loaded. 



The Running- Gear. 307 

IN INCHES BY 1.66 J THEN MULTIPLYING THE ELAS- 
TICITY IN SIXTEENTHS BY THE BREADTH OF PLATE 
IN INCHES, AND BY THE CUBE OF THE THICKNESS IN 
SIXTEENTHS : DIVIDE THE FORMER PRODUCT BY THE 
LATTER. THE QUOTIENT IS THE NUMBER OF PLATES. 

Question 295. How can we find the working strength, 
that is the greatest weight it should bear in practice, of a 
given steel-plate spring f 

Answer. By multiplying the breadth of plates 
IN inches by the square of the thickness in six- 
teenths, AND BY THE NUMBER OF PLATES ; MULTI- 
PLY, ALSO, THE WORKING SPAN IN INCHES BY 11.3 : 
DIVIDE THE FORMER PRODUCT BY THE LATTER. THE 
RESULT IS THE WORKING STRENGTH IN TONS (OF 2,240 
POUNDS) BURDEN. 

Question 296. Bow can we find the span due to a given 
strength, and number and size of plate ? 

Answer. By multiplying the breadth of plate 

IN INCHES BY THE SQUARE OF THE THICKNESS IN 
SIXTEENTHS, AND BY THE NUMBER OF PLATES ; MUL- 
TIPLY, ALSO, THE STRENGTH IN TONS BY 11.3 : DI- 
VIDE THE FORMER PRODUCT BY THE LATTER. THE 
RESULT IS THE WORKING SPAN IN INCHES. 

Question 297. How can we find the number of plates 
due to a given strength, span and size of plates ? 

Answer. By multiplying the strength in tons 

BY THE SPAN IN INCHES, AND BY 11.3 J MULTIPLY 
ALSO, THE BREADTH OF PLATE IN INCHES BY THE 
SQUARE OF THE THICKNESS IN SIXTEENTHS : DIVIDE 
THE FORMER PRODUCT BY THE LATTER. THE RE- 
SULT IS THE NUMBER OF PLATES. 

Question 298. How can we find the required amount 
of curvature or set of the spring before it is loaded ? 



308 Catechism of the Locomotive. 

Answer. By multiplying the elasticity, per 
ton, in inches, by the working strength in 
tons ; add the product to the desired working 
compass. The sum is the whole original set, 
to which an allowance of j to f in. should be 
added to the permanent setting of the spring. 

Question 299. How are the spring-hangers attached 
to the ends of the springs ? 

Answer. A great variety of methods have been used. 
The most common ones are those shown in fig. 169. 
There the hanger embraces the spring at the ends, 
g, g, (shown on an enlarged scale at a, in figs. 176 and 
178.) The end of the spring has two projections 
forged on its end to receive the upper end of the 
hanger, which is made to fit the groove thus formed 
between the two projections. The other end, b, of 
the spring, figs. 176 and 178, has an eye cut in it 
which receives the hanger b. The latter is made of a 
single bar, and also has an eye, c, to receive a key 
which sustains the weight suspended on the hanger b. 
The back end of the front springs and the front end 
of the back springs are made in this way because they 
come on the side of the fire-box, and if their width 
was increased by the thickness of the hanger, as shown 
at a in fig. 178, it would rub against and wear the 
outer shell of the fire-box. 

Question 300. How are the lower ends of the hangers 
attached '? 

Answer. The front hanger, g, fig. 169, of the front 
spring, and the back hanger, g, of the back spring 
have eyes and pins in their lower ends, k, as shown 
in the engraving. The pins are supported by rubber 
springs, /, l } which are held between two conoave cast- 



The Running- G-ear. 309 

ings, n, k, one of each of which rests against the 
frames. The object of the rubber springs is to re- 
lieve the spring-hangers from sudden shocks and 
strains. The benefit derived from their use is be- 
lieved to be purely imaginary, as the spring itself, if 
sufficiently elastic, should absorb the sudden shocks 
which the wheels and axles will convey to the hangers. 

Question 301. Why are the ends g', g / of the springs 
attached to the lever* A A? 

Answer. Because if there is a spring for every axle 
and the hangers are fastened to the frame, then evi- 
dently the locomotive has as many points of support 
as it has axle-boxes. Every shock from the rails is 
transferred through the wheel and the axle to the 
nearest axle-box and the spring belonging to it, and 
the latter must be made strong enough to receive and 
dispose of the whole of it. If the adjacent hangers, 
g', g', fig. 169, of the adjoining spriugs, B and B% are 
connected by an equalizing lever, A A, which turns 
on the fixed point C, then the shock which affects one 
wheel will be transferred first to the corresponding 
spring. From this spring a part of the shock will be 
transferred to the frame by the hanger g, and a part 
by the hanger g' to the equalizer, which will transfer 
the pressure to tht adjoining spring B'. If by some 
unevenness of the road or a powerful oscillation of the 
locomotive, a spring is momentarily burdened, the 
equalizer thus causes the next wheel to receive part 
of this load. 

The advantages of this arrangement are evident : 
since the springs have to receive only a part of the 



* This lever is called an equaiizing lever or beam, or, more briefly, an 
e g w ert lto cr. 



310 Catechism of the Locomotive. 

shocks, they can be made less strong and therefore 
more flexible. The danger of running off the track 
and that of breaking axles, springs and hangers, is 
therefore reduced by the use of equalizing levers. 

Question 302. How are the equalizing levers con- 
structed ? 

Answer. They are made of wrought iron and are 
supported in the centre by a fulcrum, G, which is 
fastened to the frame or boiler or both. The spring- 
hangers g', g / are usually attached to the lever by eyes 
and keys. Sometimes eyes are made in the lever, as 
shown in fig. 169, and the hanger is inserted into the 
eye and held either with a key or else with projections 
which are forged on the hanger below the lever. In 
other cases the hangers are made with an eye which 
embraces the end of the lever. 

Question 303. How is the distribution of weight of 
the engine affected by the equalizing levers ? 

Answer. The weight is equally distributed on all 
the driving-wheels. This is apparent if it is observed 
that the weight suspended from each of the spring- 
hangers of each spring in fig. 169 must be the same ; 
for if the weights in the two hangers, g / and cf, were 
unequal, then the end of the spring which supports 
the heaviest weight would be drawn down until the 
pressure was equalized. If the weights suspended 
from the two hangers, g' and g / , attached to the equal- 
izing lever were unequal, then the one supporting the 
greatest load would draw up its end of the equalizer 
until the weights were again in equilibrium. 

Another effect of the equalizing levers is that each 
side of the locomotive is supported in such a way that 
the action is the same as it would be if it was sup- 



The Running- Gear. 



311 



ported on one point. If, for example, we have a 
heavy beam, say a piece of timber like that shown by 
A B, fig. 184, suspended at one point, C, in its cen- 
tre, to the middle, a, of a long spring, D E, the ends 





312 Catechism of the Locomotive. 

of which rest on two supports, F and G, it is evident 
that if the point of suspension is at the middle, C, of 
the timber and a of the spring, the weight of the timber 
will rest equally on the two supports, jFand G, and that 
the ends of the timber can move up or down or vibrate 
about the point of suspension, O, without affecting the 
distribution of weight on the supports, F and G. If, 
now, the timber is suspended from three points, A, C 
and B, fig. 185, that is, its middle and two ends, as 
shown in fig. 185, the ends, A and B, being attached 
to the ends of the springs b c and d e, the latter rest- 
ing on the supports F and G, and connected at their 
opposite ends to an equalizer, f g, whose fulcrum is at 
a, it is evident that each of the end hangers must sup- 
port one-half of that part of the weight of the timber 
between it and the middle, and that the centre hanger 
must support one-half the weight between the middle 
and the two ends. Thus the hanger A b must sup- 
port one-half the weight of the timber between A and 
C, and B e must support one-half of that between B 
and C; in other words, the end hangers would each 
sustain one-fourth of the weight of the timber and 
the middle one-half of its weight. If the weight of 
the timber is 1,000 pounds, the end hangers would 
each sustain 250 and the middle one 500 pounds. 
The weight of the middle of the timber is hung on 
the equalizer, and one-half, or 250 pounds of it is thus 
transferred to each of its ends f and g, and thence to 
the hangers f c and g d, and thus to the springs, so 
that the ends, c and d, of the springs, sustain a weight 
of 250 pounds, therefore, as the opposite ends also sus- 
tain the same weight, it is evident that each of the 
springs bears a total load of 500 pounds, or one-half 



The Running- Gear. 313 

of the weight of the timber, which is the same load 
they sustained in fig. 164. If the ends of a timber 
supported as shown in fig. 185 are moved up or down 
about the centre point of suspension, it is evident that 
the distribution of weight would not be affected any 
more than it was in fig. 164 by a similar movement, 
because if the ends of the timber move as shown by 
the dotted lines around the centre point of suspension 
G, the end A will ascend as much as B descends. 
The same thing is true of the ends b and e of the 
springs and of their opposite ends c and d, and also 
of the ends of the equalizer, so that when the timber, 
springs and equalizer are in the position shown by the 
dotted lines, it is in equilibrium, just as it was when 
the timber was horizontal ; and therefore the weight 
on the supports is the same in both cases, thus show- 
ing that the load A B can move about the centre of 
suspension when supported as shown in fig. 185 as 
freely as it can if arranged as shown in fig. 184. It 
therefore follows that in the distribution of the weight 
of each side of the locomotive on the wheels and on 
the track, it may be regarded the same as though it 
was supported at one point, which is the fulcrum of 
the equalizing-lever. 

Question 304. What advantage results from support- 
ing the weight of the back part of the locomotive on two 
points ? 

Answer. If the back part of the locomotive rests on 
only two points and the front end on the centre of the 
truck, then the whole weight of the engine will be 
sustained on three points. Now it is a well known 
fact that any tripod, like that on which an engineer's 
level is mounted, or a three-legged stool, will adjust 
27 



314 Catechism of the Locomotive. 

itself to any surface, however uneven, and stand firmly 
in any position ; . whereas if there are more than three 
points of support, if they are all of the same length 
the surface on which they rest must be a plane, other- 
wise some of them will not touch. All railroad tracks 
have inequalities of surface, and therefore it is of the 
utmost importance that a locomotive should be able to 
adjust itself on its points of support to any uneven- 
ness of the track on which it must run. This is possible 
only when the weight rests on three points of sup- 
port. 

Question 305. How is the truck constructed^ 
Answer. It consists, as has already been stated, of 
two pairs of wheels.* These are attached to a frame, 
b' b', plates I, II and III. The axles have boxes 
called truck-boxes, and brass bearings similar to those 
used on the driving-axles. These boxes work in jaws, 
also similar to those on the main engine frame, ex- 
cepting that they have no attachment to prevent them 
from being worn by the motion of the boxes up and 
down in the jaws. Fig. 186 is a horizontal section, 
fig. 187 a plan, and fig. 188 a transverse section f of a 
truck. The frame G D E F. fig. 187, shown also at 
h' h\ figs. 186 and 188, is of rectangular form and is 
forged in one piece. The legs ff which form the 
jaws for the boxes, are bolted to the frame as shown 
in fig. 186. To the lower end of these legs a brace, 
g g g, is bolted, which thus unites them together. 
On each side one spring, S F S, is placed under the 



* In some rare cases three pairs of wheels are employed for locomo- 
tive trucks. Six-wheeled trucks are very commonly used under passen- 
ger cars. 

t The right half is a section through the oentre of the axle, or of G g, 
of fig. 186, and the left half a section through the centre of the truck, or 
on g g, of fig. 186. 



FLglt 




% inch = 1 foot. 



316 Catechism of the Locomotive. 

frame and in the reverse or inverted position to that 
of the driving-springs. A pair of equalizing levers, 
G G G, is placed on each side of the truck, one of them 
on the inside of the frame and the other on the out- 
side, as shown in the plan. The ends of these equal- 
izers rest on the top of the truck-boxes, and the 
springs are attached to the levers at i % by the hangers, 
j j. The truck-frame rests on the top of the spring- 
strap, F, which is made of the form of an arc of a cir- 
cle, or " rounded" as it is termed by workmen, so that 
it can move freely about the point of support. It is 
evident that this arrangement of spring and equalizer 
operates in the same way as that employed for the 
driving-wheels in distributing the weight on each of 
the wheels, and that the truck-frame is supported on 
two points, k, k, figs. 186 and 187. The weight of the 
front end of the engine rests on a cast iron centre- 
plate, H H. This centre-plate rests on four bars, / I, 
1 I, and m m,m m, two of which are bolted to the frame 
transversely and the other two longitudinally, as shown 
in the plan. These bars are elevated in the centre as 
shown in figs. 186 and 188. The transverse bars are 
trussed with two corresponding bars, n n, fig. 188, be- 
low. These truss-bars as they are called, are bolted to 
the upper bars with bolts, o, o, but are separated from 
the top-bars by distance pieces, P, P, figs. 186 and 188. 
The centre-plate H H, called the the lower centre-plate, 
has an annular groove in it, which receives a corres- 
ponding projection on the casting K K, called the up- 
per centre-plate, which is bolted to the bed-plate of the 
cylinders, as shown in plate II. The upper centre- 
plate has a pin, y, called a centre-pin, fig. 186 and 
plate II, attached to it, which passes through the lower 



The Running- Grear. 317 

centre-plate, and has a key underneath the latter 
plate. This key is intended to prevent the engine 
from " jumping" off of the truck on a rough track or in 
case of accident. The annular groove and the projec- 
tion which fits into it are intended to receive the 
strain which otherwise would bear against the centre- 
pin and would be liable to break or bend it. 

From this description it will be seen that while the 
truck-frame rests on two points, k and k, the weight of 
the engine is supported by the centre-plate of the 
truck. As the back part substantially rests on the 
centres of the two equalizers, it will be seen that this 




Scale % in 



distribution of the weight fulfills the conditions of the 
tripod, or as it has been called, the " three-legged prin- 
ciple." 

Question 306. How are trucks arranged so as to give 
them lateral motion ? 

Answer. When this is done, the lower centre-plate 
is usually suspended in some way from the truck-frame 
on links or hangers, so that it can swing laterally. 
One method of doing this is shown in figs. 189, 190 
and 191. Fig. 190 is a front view, fig. 191 a plan, 
27* 



318 



Catechism of the Locomotive. 



and fig. 189 a transverse section of such an arrange- 
ment. The centre-plate H H has cast with it an 
extension, B B, the ends of which are suspended on 
links, L, L, called suspension-links, the upper ends of 
which are attached to bars, m, m, which are set edge- 
ways and extend across the truck-frames. It is evi- 
dent that with this arrangement the lower centre 
casting can swing crosswise of the track on the links 
L, Z, and that the front end of the engine will thus 
have a lateral motion independent of the truck. 



PART XIII. 
ADHESION AND TRACTION. 

Question 307. What is meant by the " adhesion f of 
a locomotive f 

Answer. It is the resistance which prevents or op- 
poses the slipping of the driving-wheels on the rails, 
and is due to the friction of the former on the latter. 

Question 308. On what does the amount of this fric- 
tion depend? 

Answer. Like all friction it depends upon the 
weight or pressure of the surfaces in contact, and con- 
sequently upon the load which rests on each wheel. 
It also depends upon the condition of the rails, and 
probably to some extent upon the material of which 
they and the tires on the wheels are made. 

Question 309. How much force is required to make 
the driving-wheels of a locomotive slip on an ordinary 
railroad track f 

Answer. The force required to make them slip will, 
as already stated, vary very much with the condition 
of the rails. If they are quite dry and clean it will 
require a force equal to about one-fourth the weight 
on the wheels. That is, supposing we have a wheel, 
A B, fig. 192, attached to a frame which is fastened so 
that it cannot move, and that the wheel rests on a rail 
and is loaded with say 10,000 pounds, if now a rope or 
chain could be attached at a point, B, exactly at the 



320 



Catechism of the Locomotive. 



tread of the wheel, and carried over a pulley, G, then 
it would require a weight, D, of about 2,500 pounds 
attached to the end of the rope to make the wheel 
slip. If the rails were sanded, the adhesion would be 




Scale x /i ln.=l foot, 
^ooiewhat greater, and if they were wet or muddy or 
greasy, considerably less. For ordinary circumstance* 
the adhesion may safely be assumed to be one-fifth qf 



Adhesion and Traction. 321 

the weight of the driving-wheels. Of course the total 
weight on all the driving-wheels must be taken in cal- 
culating the adhesion. Thus, if a locomotive has four 
driving-wheels and each one of them bears a load of 
10,000 pounds, then the total weight on the driving- 
wheels, or adhesive weight, as it is called, will be 
10,000x4=40,000 pounds, and the adhesion will be 

40,000 

=8,000 pounds. 

5 

Question 310. What is meant by the tractive power 
of a locomotive ? 

Answer. It is the force with which the locomotive 
is urged in a horizontal direction by the pressure of 
the steam in the cylinders, and which therefore tends 
to move the locomotive and draw the load attached to 
it. 

The tractive power is of course due to the pressure 
of steam on the piston, and therefore its amount is 
dependent upon the average steam pressure in the cyl- 
inder, on the area of the piston, and also on the dis- 
tance through which the pressure is exerted, or, in 
other words, on the stroke of the piston. Thus if we 
have a cylinder 16 inches in diameter and two feet 
stroke and an average steam pressure of 50 pounds 
per square inch, then as the area of such a piston 
would be 201 square inches, the average pressure on 
it would be 201x50=10,050 pounds, and as each pis- 
ton moves through four feet during one revolution of 
the wheels, the number of foot-pounds of energy ex- 
erted by it would be 10,050x4=40,200, and for the 
two cylinders of a locomotive double that amount, or 
80,400 foot-pounds. Now if the driving-wheels are 



322 Catechism of the Locomotive, 

five feet in diameter, their circumference will be 
15.7 feet, and therefore the locomotive will move 
that distance on the rails during one revolution, if the 
wheels do not slip. The 80,400 foot-pounds of energy- 
is therefore exerted through a distance of 15.7 feet, 
and therefore 

80,400 

=5,121 pounds, 

15.7 
which is the force exerted through each foot that the 
circumference of the wheel revolves and the locomo- 
tive moves. If the wheels were only half the diam- 
eter, or 2| feet, then their circumference would be 
7.85 feet and the tractive power would be 

80,400 

=10,242 pounds, 

7.85 
or double what it was before. It will be seen, then, 
that the tractive force of a locomotive is dependent 
upon (1) the average steam pressure in the cylinders, 
(2) the area, (3) the stroke of the pistons, and (4) the 
diameter of the driving-wheels. 

Question 311. How is the tractive power of a loco- 
motive calculated? 

Answer. By multiplying together the area of 

THE PISTON IN SQUARE INCHES, THE AVERAGE STEAM 
PRESSURE IN POUNDS PER SQUARE INCH ON THE PIS- 
TON DURING THE WHOLE STROKE, AND FOUR TIMES 
THE LENGTH OF THE STROKE OF THE PISTON,* AND 
DIVIDING THE PRODUCT BY THE CIRCUMFERENCE OF 

the wheel. The result will be the tractive power 



* This length may be taken in feet, inches or any other measure, bat 
in making the calculation the circumference of the wheel must be taken 
in the same measure as the stroke of the piston. 



Adhesion and Traction, 323 

exerted in pounds. The adhesion must of course al- 
ways exceed the tractive force, otherwise the wheels 
will slip. 

Question 312. How is the locomotive made to ad- 
vance by causing the wheels to revolve ? 

Answer. The pressure of steam in the cylinders is 
exerted in one direction against the piston, and in the 
opposite direction against the cylinder head, as shown 
in fig. 192, in which the steam is represented by the 
dotted shading in the back end of the cylinder, and 
the direction of the pressure by the darts s, s. The 
pressure against the piston is communicated by the 
connecting-rod to the crank-pin E, and that on the 
cylinder-head is carried to the axle by the frame F F*, 
and the direction of the two forces is indicated by the 
two darts, a and b. We may now regard the spokes 
of the wheels as acting as levers, and assume that the 
fulcrum is either at the centre G of the axle, or at B, 
the point of contact of the wheel with the rail.* We 
will assume that it is at the centre G of the axle and 
for the sake of even figures that the wheel is six feet 
in diameter and cylinders have two feet stroke. We 
will also suppose that the engine is supported so that 
the wheels do not touch the rails, and that a chain or 
rope passing over a pulley G is attached to the wheels 
at B and with a weight at D. We now have a force, 
a, of 10,000 pounds exerted on the crank-pin, or at 
the end of the short arm E G of the lever E G B. 



• The question whether the centre of the axle or the point of contact 
with the rail is the fulcrum of the lever in this case has been the subject 
of much animated discussion and contention. As the word fulcrum 
means " a point about which a lever moves," it is believed that the dis- 
pute is due simply to a difference in the meaning assigned to the word 
fulcrum. If we regard the fulcrum as the point which is fixed in rela- 
tion to the locomotive, then it is at the centre of the axle, but if we ] 
it to the surface of the earth, then it is at the top of the rail. 



324 Catechism of the Locomotive. 

As E G is one foot and G B three feet long, 10,000 
would be balanced by 

10,000x1 

=3,333 pounds, 

3 
at B. In other words, it would require 3,333 pounds 
suspended from the chain at D to resist the strain at 
E. But when this is the case, the pressure of the axle 
at the fulcrum, in the direction of the dart c, is equal to 
the pressure against the crank-pin E added to that 
exerted by the weight D at B, or 10,000-' 3,333= 
13,333 pounds. 

As the pressure against the axle in the opposite di- 
rection, b, is only 10,000 pounds, there will be an un- 
balanced force of 3,333 pounds acting in the direction 
of the dart c, and tending to move it that way. As 
the axle is attached to the locomotive frame, this force 
will of course have a tendency to move the whole ma- 
chine, and is really the tractive force of the engine. 

If, on the other hand, we regard the point of contact 

B of the wheel with the rail as a fulcrum, we have a 

force of 10,000 pounds acting against a lever, E G B, 

four feet long. There would therefore be a force, c, of 

10,000x4 

=13,333 pounds 

3 
exerted at G, and as the pressure in the direction of 
the dart b is only 10,000, there would be an unbal- 
anced strain of 13,333-10,000 = 3,333 pounds acting 
against the axle in the direction of the dart c, or, in 
other words, there is 3,333 pounds more of force pull- 
ing the axle forward than there is pushing it backward. 

When the crank-pin is below the axle, in the posi- 
tion shown in fig. l^fy then if the centre of the axle 



Adhesion and Traction, 325 

is regarded as the fulcrum we have a pressure of 
10,000 pounds pushing against the front cylinder- 
head, which is transferred to the axle hy the frames, 
and acts in the direction of the dart c, and we also 
have a pressure against the crank-pin E in the direc- 
tion of the dart a. Now 10,000 pounds at E would 
exert a force of 

10,000x1 

=3,333 pounds 



at .Band 



10,000x2 

-=6,666 pounds 



3 

at G in the direction of b. But the pressure on the 
cylinder-head pulls against the axle G in the direc- 
tion c with a force of 10,000, so that the excess of 
strain in the direction b will he equal to 10,000 — 
6,666=3,333 pounds. If we regard B as the fulcrum, 
the calculation is exactly the same, as 10,000 pounds 
at E exerts a force at G equal to 
10,000x2 

z=.6,666 pounds, 

3 
and the difference hetween it and the pressure exerted 
hy the strain against the front cylinder-head is the 
force which urges the axle and with it the locomotive 
forward. 

It will he seen, then, that it is immaterial which point 
is regarded as the fulcrum, as the result of the calcu- 
lations is exactly the same. 

It must not, however, be hastily supposed from 
what has been said that the total pressure against 
the axle can be greater than its resistance to the pres- 
28 



326 



Catechism of the Locomotive, 



sure. As soon as the one exceeds the other it will 
move. But supposing that it requires a force equal to 
3,333 pounds to draw a train coupled to the engine. 
as soon as the difference between the force exerted 







Scaled ln.=l root, 
against the axle by the piston to move it forward anc 
that which presses it back exceeds 3,333 pounds, the 
locomotive will move the train. If it continues tc 



Adhesion and Traction. 327 

exceed it the speed of the train will be accelerated and 
thus the resistance which holds the engine back and 
that which pushes it forward will always be equal. 

Question 313. Does the fact that the piston is work- 
ing from the end of a longer lever E G' B, fig. 192, when 
the crank-pin is above the axle, enable the locomotive to start 
a heavier train than when the crank-pin is below the axle 
and the piston is working against a shorter lever, G E B, 
fig. 193? 

Answer. No ; because, as has already been shown, 
the pressure against the axle is the same in both cases. 
It is in fact only during the forward stroke that the 
pressure on the crank-pin moves the engine forward. 
The forward pressure which is exerted by the crank- 
pin at the axle is then greater than that exerted 
against the latter in the opposite direction by the cyl- 
inder-head and frames. It is this excess of crank 
pressure which moves the engine and which is the 
tractive force during the forward stroke. During the 
backward stroke the piston is pushing the axle back- 
ward, and the pressure against the front cylinder-head 
is pulling it forward. The latter then exceeds the 
former, and the difference between the two is the force 
which moves the engine forward. As has been shown, 
this difference is the same in both positions of the 
crank, and therefore the locomotive can not from this 
cause pull more when the crank is above the axle than 
when it is below. 



PART XIV. 

INTERNAL DISTURBING FORCES IN THE 
LOCOMOTIVE. 

Question 314. What are the internal disturbing forces 
in a locomotive ? 

Answer. They are : 1, the momentum of the parts 
which have a reciprocating motion; 2, those due to 
the varying pressure of the steam in the cylinder- 
heads ; 3, those caused by the thrust of the connecting- 
rods against the guide-bars ; and 4, those produced 
by unbalanced revolving parts. 

Question 315. How can the effects of these disturbing 
forces be neutralized? 

Answer. By putting counterweights, A, A, fig. 161, 
in the driving-wheels opposite the crank-pins. The 
motion of these will then be in the reverse direction 
to that of the weight of the parts attached to the 
crank-pins, and the motion of the one will thus, to 
some extent, at least, neutralize the disturbing influ- 
ence of the other. 

Question 316. Can the weight of these counterweights 
be calculated for any locomotive ? 

Answer. It can probably be calculated, but it is an 
exceedingly complicated problem, and one about which 
there is much difference of opinion. The difficulty is 
also increased by the fact that while counterweights 
may be heavy enough for one speed, they may be too 



Internal Disturbing Forces. 329 

heavy or too light for a slower or faster speed, and 
quite disproportioned when the engine is not working 
steam. The following rules are given in "Clark's 
Railway Machinery," and are perhaps sufficiently close 
to find a first approximation to the requisite position 
and weight of the counterweights ; but the final ad- 
justment should be made by trial. This can be done 
by suspending the locomotive by chains attached to 
the four corners of its frame, and setting the ma- 
chinery in motion at the speed it is intended to run. 
By attaching a pencil to one or to each of the four 
corners of the frame, and arranging it so that it will 
mark on a horizontal fixed card, a diagram will be 
drawn, being usually an oval, which will show the 
amount and form of the oscillations. The counter- 
weights can then be adjusted so that the diagram drawn 
by the pencil is reduced to the least possible size. 
When the adjustment is successful, the diameter of 
the diagram is reduced to about ^ of an inch.* An- 
other and simpler, but less accurate, way is to place a 
pail or other vessel filled with water on the front 
of the engine and run the locomotive on j*. smooth 
track at a high speed, and adjust the counter- 
weights so that the least amount of water will be 
spilled. 

Question 317. How can the centre of gravity of a 
counterweight in one segment be found? 

Answer. By cutting a wooden templet of uni- 
form THICKNESS TO THE FORM OF THE SURFACE, 
AND FREELY SUSPENDING IT BY ONE OF THE COR- 
NERS, a, as in fig. 194; a plummet-line, P a, 

DROPPED FROM THE SAME POINT OF SUSPENSION 



* Rankine's Treatise on the Steam Engine. 

28* 



330 



Catechism of the Locomotive* 



IN FRONT OF THE TEMPLET WILL INTERSECT TH% 
CENTRE LINE Jc AT THE CENTRE OF GRAVITY C. 

Question 318. Bow can the centre of gravity of a 
counterweight in three segments be found? 

Answer. Find the centre of gravity (?, fig. 
195, of one of the counterweights, as ab^vej 



( 
Fig. 

i / 
y 
/ \ 

\ \ 


19 4. 

a 

CC \ 

\ \ 
\ \ 
\ \ 

\ \ 
\ \ 
s. \ \ 



THROUGH G STRIKE AN ARC FROM THE CENTRF//7, 
OF THE WHEEL, CROSSING THE CENTRE LINES OF 
THE OTHER SEGMENTS AT THEIR CENTRES, C C"; 
DRAW C C" MEETING A B AT Z>, AND SET OFF 
D B, ONE-THIRD OF THE INTERVAL D C. THEN E 
IS THE COMMON CENTRE OF GRAVITY OF THE THREE 
SEGMENTS. 

Question 319. Bow can the centre of gravity of a 
counterweight in two segments be found? 



Internal Disturbing Forces. 



331 



Answer. This is required when the crank is opposite 
to a spoke, as in fig. 196. Find the centre of 

GRAVITY, G, OF ONE SEGMENT AS BEFORE, AND BY 
AN ARC FIND THE OTHER CENTRE C ', DRAW G G / , 
CUTTING A B AT D, WHICH IS THE COMMON CENTRE 
OF GRAVITY. 




Question 320. How can the centre of gravity of a 
counterweight in four segments be found? 

Answer. Find, as before, the centres G, C', 0", 

C w , FIG. 197, OF THE SEGMENTS ; DRAW G" C / AND 
C" C, CUTTING THE LINE A B ; BISECT THE INTER- 
VAL SO INCLOSED AT E FOR THE COMMON CENTRE 
OF GRAVITY. 

Question 321. How is the counterweight for outside- 



332 



Catechism of the Locomotive. 



cylinder engines with a single pair of driving-wheels cal- 
culated f 

Answer. Find the total weight, in pounds, of 

THE REVOLVING AND RECIPROCATING MASSES FOR 




ONE SIDE, NAMELY, THE PISTON AND APPENDAGES, 
CONNECTING-ROD, CRANK-PIN AND CRANK-PIN BOSS ; 
MULTIPLY BY THE LENGTH OF CRANK IN INCHES, AND 




DIVIDE BY THE DISTANCE IN INCHES OF THE CENTRE 
OF GRAVITY OF THE SPACE TO BE OCCUPIED BY THE 
COUNTERWEIGHT. THE RESULT IS THE COUNTER- 



Internal Disturbing Forces, 



333 



WEIGHT IN POUNDS, TO BE PLACED EXACTLY OPPO- 
SITE TO THE CRANK. 

Question 322. How is the counterweight for outside- 
cylinder engines with coupled driving-wheels calculated ? 
Answer. Find the separate revolving weights, 

IN POUNDS, OF CRANK-PIN, CRANK-PIN BOSS, COUP- 
LING-RODS AND CONNECTING-ROD, FOR EACH WHEEL 
ALSO THE RECIPROCATING WEIGHT OF THE PISTON 
AND APPENDAGES, AND HALF THE CONNECTING-ROD ; 
DIVIDE THE RECIPROCATING WEIGHT EQUALLY BE- 
TWEEN THE COUPLED WHEELS, AND ADD THE PART, 
SO ALLOTTED, TO THE REVOLVING WEIGHT ON EACH 
WHEEL ; THE SUMS SO OBTAINED ARE THE WEIGHTS TO 
BE BALANCED AT THE SEVERAL WHEELS, FOR WHICH 
THE NECESSARY COUNTERWEIGHT MAY BE FOUND BY 
THE PRECEDING RULE. 

Question 323. How are the counterweights con- 
structed f 

Answer. They are usually made of cast iron, so as to 
fill or partly fill the spaces between the spokes of the 
wheel, as shown at A A in fig. 161. Each of the seg- 
ments consists of two pieces, one of which is put in 
from the outside of the wheel and the other from the 
inside. The two are then bolted together with bolts, 
which are shown in the above figure. In some cases 
the counterweights are cast solid with the wheels, and 
in others, cavities are cast in the wheels which are 
filled with lead, which is poured in when melted. 
Some locomotive builders make the rims and spokes 
of the wheels hollow and fill them with lead opposite 
to the crank-pins. It is difficult, however, to get the 
required weight in such wheels unless they are of 
large diameter. 



334 Catechism of the Locomotive. 

Question 324. What effect has the strain on the draw- 
bar, when the engine is pulling a load, upon the distribu- 
tion of the weight on the wheels ? 

Answer. It has the effect of pulling the back end of 
the engine down, and, as it is balanced on the fulcrums 
of the equalizing levers, it at the same time lifts up 
the front end. In this way the harder a locomotive 
is pulling the greater will be the weight which is 
thrown on the driving-wheels, and that on the truck 
will be correspondingly diminished. The higher the 
draw-bar is above the rails the greater will be the ten- 
dency to pull the engine down behind and up in front. 



PART XV. 

MISCELLANEOUS. 

Question 325. What is the sand-box, V, plates I and 
II for, and how is it constructed ? 

Answer. It is intended to carry a supply of dry sand, 
which is scattered on the rails in front of the driving- 
wheels when the latter are liable to slip. This is done 
by two pipes, e', e', plate I, one on each side of the en- 
gine. They lead from the sand-box to within a few 
inches of the rail. At the upper end and inside the 
sand-box they each have a valve which is operated by 
a lever which is connected to the cab by a rod which 
enables the locomotive runner to open or close the 
valve at pleasure. 

The sand-box is usually made of sheet iron with a 
cast iron base, and a top of a more or less ornamental 
design. It also has an opening on top through which 
the sand is supplied to the box. This opening has a 
loose cover to exclude rain and dirt from the sand. 
The sand-box is usually located on top of the boiler in 
front of the front driving-wheels. 

Question 326. What is the bell V for ? 

Answer. It is used for giving signals of the starting 
or approach of the engine. It also is located on top 
of the boiler and is usually hung on a cast iron 
frame and rung with a rope connecting it with the 
cab. 



336 Catechism of the Locomotive, 

Question 327. What is the weight of an ordinary 

locomotive bell? 

Answer. From 50 to 100 pounds. 

Question 328. What is a locomotive head-light ? 

Answer. It is a large lamp, T, plates I and II, 
placed in front of the locomotive to signal its approach 
at night and also to illuminate the track for the loco- 
motive runner. 




Scale 1)4 in. =1 foot. 



Question 329. How is a head-light constructed? 
Answer. The lamp has what is ealkd an Argand 



Miscellaneous. 337 

6urner ; that is, a burner with a hollow cylindrical 
wick, through the centre of which a current of air cir- 
culates, which thus supplies the flame with a larger 
quantity of air than is possible if the latter can come 
in contact with the former only from the outside. The 
result is that the combustion is much more brilliant 
than with ordinary burners. In order to throw all the 
light on the track the burner is placed inside of a con- 
cave reflector, a b c, fig. 198, which is of a parabolic 
form. One of the peculiarities of this form of reflector 
is that if a light is placed in its focus f the rays will 
be reflected from its surface in parallel lines. Thus, let 
a b c, fig. 198, represent a section of such a reflector. 
Now, if a light be placed in the focus f the rays will 
strike against the reflector, be thrown in the direction 
of the dotted lines fl x,/2x. . .f9x, etc., and thus 
be thrown directly in front of the engine. The reflect- 
ors are usually made of copper and plated with silver. 

The lamps and reflectors for head-lights are inclosed 
in a rectangular case which is supported on two brack- 
ets bolted to the front of the smoke-box. On these 
brackets a wooden shelf is fastened on which the head- 
light rests. 

Question 330. What are the running-boards and hand- 
rails ? 

Answer. The running boards are planks, i i, plate I, 
placed on each side of the boiler to enable the locomo- 
tive runner or fireman to go from the cab to the front 
end of the engine when it is running. The hand-rails, 
m m' m', are brass or iron pipes attached to the top of 
the boiler and extending from the cab to the smoke-box, 
and are placed there, as their name indicates, to support 
or for a hand-hold for persons on the running-board. 
29 



338 Catechism of the Locomotive. 

Question 331. What provision is made for removing 
from the track such obstacles as cattle or fallen rocks, 
which may be in front of locomotives? 

Answer. What is called a cow-catcher or pilot, S, 
plates I and II, is attached to the front of the loco- 
motive. This is usually made of wood, and consists 
of a triangular frame at the bottom which is sup- 
ported about four inches above the tops of the rails. 
Straight pieces of wood of about 2\ x 4 inches sec 
tion are fastened to this frame and also to a horizontal 
piece which is bolted to the bumper-timber E'. These 
pieces arranged in this way and only a few inches 
apart give to the cow-catcher a peculiar curved 
form somewhat resembling that of the mould-board of 
a plow, which is very well adapted for throwing any 
obstacles from the track. Sometimes these pieces are 
placed horizontally instead of being inclined up and 
down. Cow-catchers are also in some cases made of 
round iron bars or angle iron. They are always 
bolted securely to the bumper-timber and strengthened 
by strong iron braces attached to the bottom frame at 
the front and back. These braces are usually fastened 
at the other end to the bumper-timber, but are some- 
times attached to the bed-plates of the cylinder. 

There is also usually a strong pushing-bar attached 
with a bolt and hinged joint to the bumper-timber. 
This is shown in plates II and III in the position it 
occupies when not in use. It is used in pushing cars, 
as very often there is not room for the pilot under the 
end of the car. In using it is raised up, and the front 
end is then coupled to the draw-head of the car. 

Question 332. What is the foot-board or foot-plate of 
a locomotive ? 



Miscellaneous. 



339 



Answer. It is a wrought or cast iron plate which ex- 
tends across and rests upon the two frames at the 
back part of the locomotive and behind the boiler, 
and on which the locomotive runner and fireman 
stand. It also unites the two frames very securely, 
and furnishes an attachment for the draw-bar. The 
foot-board is often made much heavier than is neces- 
sary for strength, in order to increase the weight, 
and thus the adhesion, on the driving-wheels. It is 
a fact often not suspected that any weight placed on 
the back end of an ordinary locomotive will increase 
the load on the driving-wheels by an amount con- 
siderably greater than that ©f the weight itself. The 







Flu. 199. 




i, 


J 


/ 
1 


k- 


-D * A\ 

1 V ^ ) 
i 


I 


A 


a £ 


M i — » , i — » u 

m % 



reason of this is that the locomotive rests on the 
centre of the truck and the centres of the equalizers, 
and therefore the weight, if applied to the back end of 
the engine, gains considerable leverage. This will be 
clear if we take a beam, A B, an<^ rest it on two sup- 
ports, m and n, fig. 199. If now we put a weight W 
on the end, overhanging the point of support, the 
weight which will rest on n will be equal to that of W 
multiplied by its distance G from m and divided by 
the distance D between m and n. Thus if a foot-board 
weighs 1,000 pounds, and its centre of gravity is 5^ 



340 Catechism of the Locomotive. 

feet behind the centre of the equalizer, and the latter 
14 feet from the centre of the truck, then the 
weight thrown on the driving-wheels will be equal to 
1,000x191 

= 1,393 pounds. 

14 
The same thing is of course true of any other weight 
placed on the back end of the engine. 

Question 333. What are the " wheel-guards" of a 
locomotive ? 

Answer. They are sheet iron covers over the upper 
half of the periphery or tread of the wheels, and are 
placed there to protect the engine from the dirt and 
mud which adhere to the wheels and are then thrown 
off on the machinery by the centrifugal force. 

Question 334. What are " check " or " safety chains ?" 

Answer. There are two kinds of such chains, the 
one attached to the trucks and frames of the locomo- 
tive and the tender. The object of these chains is to 
prevent the trucks from turning around and getting 
crosswise of the track if the trucks should leave the 
rails. The other kind of safety chains connects the 
engine to the tender, so that, in case the draw-bar or 
coupling-pins should break, the two will not separate. 
Great care should be exercised to attach the truck 
chains so as to be strong enough to resist the strains 
to which they will be subjected in case the trucks run 
off the track. The grossest carelessness and igno- 
rance are often shown in the construction of these 
parts. 



PABT XVI. 
SCBEW-THKEADS, BOLTS AND NUTS. 

Question 335. How must the screws of bolts and nuts 
be made, in order to Jit each other ? 

Answer. Each size of screw must be made of exactly 
the same diameter, and their threads of the same form 
and proportions and pitch. 

Question 336. What is meant by the "pitch" of a 

thread? 

Answer. It is the distance the thread progresses 
lengthwise of the screw in one revolution. Thus if a 
single-threaded screw has one-eighth of an inch pitch, 
it means that the threads are §- of an inch apart 
measured from the centre of one thread to the centre 
of that next to iu, and therefore there are eight 
threads to each inch in length of the screw. 

Question 337. What is meant by a " single-threaded " 
screw f 

Answer. It means a screw with hut one thread in- 
stead of two or more. Thus if we take a string and 
wind it around a pencil, it will represent a single- 
threaded screw, and if we take two or three strings 
and wind them parallel to each other, they will repre- 
sent a double or treble-threaded screw. The latter 
kinds are seldom or never used on locomotives, so 
that in the following discussion only single-threaded 
-screws will be referred to. 
29* 



342 



Catechism of the Locomotive. 



Question 338. What is the usual form of the threads 
of screws ? 

Answer. The most common is what is called the 
V-thread, represented in fig. 200, which is made 
sharp at both the top and bottom. If such a thread 
for one screw is made very pointed and that for 
another is blunt, it is plain that the nut for the 
one will not fit the other accurately, and also that if a 
nut has eight threads to the inch, it will not fit on 
a bolt with nine. Owing to the fact that, until within 
a few years, no common standard has been agreed 
upon for the form, proportions or pitch of screws 
there has been very great diversity in these respects 

Fig. 200. 




Full Size. 

in the screws which have been used in the 
construction of locomotives and other machinery. 
In 1864 the inconvenience and confusion from this 
cause became so great that it attracted the attention 
of the Franklin Institute of Philadelphia, and a com- 
mittee was appointed by that association to investi- 
gate and report on the subject. That committee 
recommended the adoption of the Sellers system of 
screw-threads and bolts, which was devised by Mr. 
William Sellers, of Philadelphia. This same system 
was subsequently adopted as the standard by both the 



Screw-Threads, Bolts and Nuts. 343 

Army and Navy Departments of the United States, 
and then hy the Master Mechanics' and Master Car 
Builders' associations, so that it may now be regarded, 
and in fact is called, the United States standard, but 
the design is due to Mr. Sellers. 

Question 339. In establishing a standard system of 
screws and threads, what is the first thing which must be 
determined? 

Answer. The number of threads to the inch, or the 
pitch of the threads for screws of different diameters. 

Question 340. What is the standard for the number 
of threads to the inch for the different sized screws of the 
Sellers system ? 




Fig. 201. Full size. 

Answer. The number of threads with their other 
proportion is given in the table at the end of this 
chapter on page 348. 

Question 341. What is the form of the thread of this 
standard? 

Answer. The form is shown in fig. 201, and is simi- 
lar to the V-thread, excepting that it is flattened at 
the top and bottom. 

Question 342. What are the reasons for the adoption 
ofthisfbrm of thread? 

Answer. It has already been pointed out that if a 



344 Catechism of the Locomotive. 

screw is made with a " blunt " thread it will not fit a 
nut with very acute or u sharp" threads; or, if the 
thread of the bolt was acute and that in the nut ob- 
tuse, they would fit imperfectly. It is therefore 
necessary in a standard system to fix upon the angle 
which the sides of the thread shall bear to each other. 
This in the United States standard system was deter- 
mined by Mr. Sellers at 60 degrees, because that angle 
is easily laid off without special instruments* and is 
perhaps as good as or better than any other form for 
the threads. 

It is obvious that if a tool is ground with its sides 
at an angle of 60 degrees to each other, if the point is 
made sharp after a very little use it will be worn more 
or less so that the bottom of the thread will not be 
cut perfectly sharp, and therefore it will be difficult to 
make bolts and nuts with sharp threads fit each other 
accurately. It is also plain that the sharp edge of a 
thread gives very little strength to the screw, and yet 
diminishes that of the bolt very materially. It will 
also be impossible to measure the diameter of the 
screw at the bottom of the thread if it is made sharp, 
as its depth will vary as the point of the tool wears, 
and it is almost impossible to measure the diameter of 
such a screw accurately with ordinary calipers. A 
sharp-edged thread in a bolt is also very liable to be 
injured and bruised by coming in contact with other 
objects. To obviate these evils the standard threads 
are therefore made flat on the top, and it is evident 
that a similar shape at the bottom will give increased 



* This can be done by drawing a circle of any diameter, and subdi- 
viding the circumference into six equal parts with the radius. Lines, 
drawn from the points of division to the centre will have an inclination 
of 60 degrees to each other. 



Screw-Threads, Bolts and Nuts. 345 

strength to the holt as well as conform to and fit the 
thread in the nut. To give this form requires only 
that the point of the cuttiDg tool shall be taken off, 
and then it is evident this form of thread can he cut 
in a lathe with the same tool and in the same manner 
as the sharp thread. The width of the flat top and 
bottom should of course bear a definite proportion to 
the size or pitch of the thread. 

Question 343. What are the proportions, of the 
standard threads ? 

Answer. The rule given by Mr. Sellers for propor- 
tioning the thread is as follows : " Divide the pitch, 

OR, WHAT IS THE SAME THING, THE SIDE OF THE 



Fig. 202. 

THREAD, INTO EIGHT EQUAL PARTS; TAKE OFF ONE 
PART FROM THE TOP AND FILL IN ONE PART IN 
THE BOTTOM OF THE THREAD : THEN THE FLAT TOP 
AND BOTTOM WILL EQUAL ONE-EIGHTH OF THE 
PITCH, THE WEARING SURFACE WILL BE THREE- 
QUARTERS OF THE PITCH AND THE DIAMETER OF 
SCREW AT BOTTOM OF THE THREAD WILL BE EX- 
PRESSED BY THE FORMULA \ 
1.299 

diameter 



no. threads 'per inch. 



846 CatecKum of the Locomotive, 

In order to make the form and proportions of this 
standard thread as plain as possible, we have had an 
enlarged diagram, fig. 202, engraved, so a3 to represent 
the different parts clearly, x represents the pitch, d 
the diameter of the screw in inches, v the number of 
threads to the inch, n the diameter at bottom of 
thread, m the width of back part of thread at the top 
and bottom, and s the length of the side of thread. 

From Mr. Sellers' rule the following formulae can be 
deduced : 



n=d 



1,299 



8 
3x 

From this rule any thread can be constructed, it 
being only necessary to know the pitch or number of 
threads to the inch. This, with all the dimensions of 
the standard threads for bolts from J to 2 inch diame- 
ter, is given in the table on page 348. 

For practical use in the shop a gauge like that shown 
in fig. 203 will be found most convenient for grinding 
the tools to the proper form for making the standard 
screws. With this gauge the screw-cutting tool can 
first be ground to the proper angle by fitting it to the 
deepest notch, and the requisite quantity should then 
be taken off the point by fitting it to the notch repre- 
senting the form of thread for the sized bolt or num- 
ber of threads to the inch which it is intended to cut. 

Wherever this standard for threads is used, if any pre- 
tense at all is made to accuracy of workmanship, care- 



Screw- Threads, Bolts and Nuts. 347 

ful attention should be given to the form and propor- 
tion of the threads as well as to the number to the 
inch. In buying taps and dies the purchaser should 
see that they conform in every respect to the standard, 
and in making specifications for new work similar 
care should be exercised to secure the true standard, 
form and proportion of screws. In many shops the 
workmen who have the care of those tools are entirely 
ignorant of the peculiarities of the Sellers system, and 
have only the vague idea that so long as they get the 




Pig. 203. Full size. 

proper number of threads to the inch they are doing 
all that is necessary to secure uniformity. Unless, 
therefore, some care is exercised to insure accuracy of 
workmanship in this department, the adoption of a 
"standard" for screws will not insure the advantages 
which would result from uniformity of screws and 
threads. 



348 Catechism of the Locomotive. 

Question 344. Bow thick must a nut be, measuring 
lengthwise of the bolt, so that the thread in the nut will be 
of equal strength to that of the bolt % 

Answer. Its thickness must be equal to the outside 
diameter of the screw. 

TABLE GIVING PROPORTIONS OF THE UNITED STATES OR SELLERS 
STANDARD SYSTEM OF SCREW-THREADS. 



o 


% 


« 


£ 


G 


3 


« 


^ 


El 

a & 
2 5 


il 

ere 

: o 


gig 

R 2 


po2 

pp ms 
: & c? 


is 

/; gs 


CD 

o 


» 2 H 

2 2° 
M o 


p o JS 

Pert? 

i-»2> 

~89 




B 




O p"-*i 


* p'^ 


| 


I1> 


2.&C 


: &"* 




o 
I-* 

8 


: & 

! * 


P O 

5 ® 

Op P 


: s£ 

: B? 


CD 

l-S 

o 

8 


g 

p 
p. 


g9 ^ o 

P^cd 


ill 






. « 


n- 


: »g- 


3 


•d 


r*- 


: co g" 




3 


• CD 


* S'» 


: 2,B 


€ 


CD 


- P CD 


: 2,B 


A 


20 


.185 


.0062 1 


J 




.837 


.0156 


18 


.240 


.0074 


8 i 




.940 


.0178 


% 


16 


.294 


.0078 ] 




1.065 


.0178 


7-16 


14 


.344 


.0089 : 


% * 




1.160 


.0208 


9^6 


13 


.400 


.0096 : 


*2 c 




1.284 


.0208 


12 


.454 


0104 


^ 


1389 


.0227 


%, 


11 


.507 


.0113 ] 




1491 


.0250 


"i 


10 


.620 


.0155 1 


% £ 




1.616 


.0250 


9 


.731 


.0138 2 


4 


H 


1.712 


.0277 



PART XVII. 
TENDERS. 

Question 345. What are locomotive tenders for? 

Answer. They carry a supply of fuel and water for 
locomotives while they are running. 

Question 346. How are they usually constructed? 

Answer. Their construction is represented in figs. 
204, 205 and 206. Fig. 204 is a side view, fig. 205 a 
longitudinal section, and fig. 206 a plan of an ordinary 
tender, which consists of a frame, A A A A, made of 
wood or iron,* mounted on a pair of trucks, T, T. 
The top of the frame is covered with planks, B, B, 
which form the floor of the tender. On top of this 
floor a sheet-iron tank, G O G, is placed, which car- 
ries the supply of water. This tank is made some- 
what in the form of a letter z> , as shown in the plan. 
It is made in this way so that the space between the 
two branches, G, G, or " legs," as they are called, will 
give room for fuel. Around the upper edge of the 
tank a sheet-iron rim, D D, is riveted, so as to pre- 
vent the fuel from falling off when it is filled up above 
the top of the tank. 

Question 347. How is the tank filled with water? 

Answer. There is a round opening, E, called a man- 
hole, on top. Into this the end of a leather or canvas 



* The frame represented in the engraving is made of wood. In the 
plan it is shown by dotted lines. 

30 



360 Catechism of the Locomotive. 

hose is introduced, which is attached to a stationary 
tank, at a water station, and a stream of water is then 
allowed to flow through the hose into the tank of the 
tender. 

Question 348. How is the water conducted from the 
tender to the engine ? 

Answer. To each side of the front end of the tank, 
one end of a piece of rubber hose, F F, is attached, 
which is connected at the other end to the pipe on the 
engine which supplies the pump with water. The 
opening inside the tank through which the water 
flows to the hose is covered with a valve, which is not 
shown in the engraving, but which is operated by a 
lever or handle, G. The valve is covered with a hood 
or strainer, perforated with small holes, which is in- 
tended to prevent dirt from entering the hose and thus 
getting into and obstructing the pump. The hose is 
connected to the supply pipe by a screw-coupling sim- 
ilar to that used with ordinary fire-engine hose. 

Question 349. How are the fiat sides of the tank 
strengthened so as to resist thd pressure and weight of the 
water ? 

Answer. They are sometimes braced or stayed with 
rods or bars, a, a, and h, h, fig. 205, extending from 
one side to the other and from the top to the bottom, 
and angle or T iron is also riveted to the sides to stiffen 
them. 

Question 350. How is the tender connected to the en- 
gine ? 

Answer. By the draw-bar, H, and coupling-pin, o, 
fig. 205, and also by the safety chains, d. 

Question 351. In what respect do the tender trucks 
differ from the engine truck t 



354 



Catechism of the Locomotive. 



Answer. Chiefly in having the journal-bearings and 
frames outside of the wheels. 

Question 352. Why are the hearings placed outside 
instead of inside f 

Answer. Because they are then more accessible than 
if they are inside, and the oil-boxes on the axles can 
be entirely closed over the ends of the axles, so that 




Pig. 208. Scale A ^.=1 inch. 



Tenders. 



355 



no oil can leak out, whereas if the boxes are inside, 
they must be left open at both ends. When the boxes 
are on the outside, they can be oiled, or a journal- 
bearing can be removed and a new one put in its 
place, with much less difficulty than if the boxes were 
on the inside of the wheels. The only reason why the 
bearings of engine truck-axles are placed inside the 
wheels is because they would be in the way of the 
cylinders if they were outside. 

Question 353. How are the axle-boxes for the tender 
axle constructed. 

Answer. Their construction is similar to that of a 
car axle-box, the standard form of which is repre- 
sented in figs. 207, 208 and 209. Fig. 207 is a sec- 




Fig. 209. Scale 3% in.=l inch, 
tion lengthwise of the axle, fig. 208 a section crosswise 
of the axle, and fig. 209 a sectional plan. A is the 
journal of the axle, which is inclosed by a cast iron 
box, K K, which is open in front and at the back. 
The front has a cover, H. which is either fastened by a 



356 Catechism of the Locomotive. 

spring, as shown in the illustrations, or is bolted to 
the box. The axle enters the box from the back, 1, 
and has either a wood or leather packing, J J, called 
a dust-guard, to keep the dust from getting in and the 
oil from leaking out of the box. D is a brass journal- 
bearing, which rests against a cast iron bearing piece 
or key, E, which is put in so that by removing it 
through the opening F F, the brass bearing can be 
raised up high enough to clear the collar, G, on the 
end of the axle and thus be removed in the same way. 
The lower portion, L, of the box under the axle is 
usually filled with cotton or woolen waste saturated 
with oil. This constantly presses against the axle, 
and thus keeps it oiled. 

Question 354. How are the tender trucks constructed ? 

Answer. They are made of various patterns, some of 
which have wooden frames and in other cases the 
frames are made of iron. The truck illustrated in our 
engraving, figs. 204 and 205, is made of iron and is 
very similar to the engine truck, excepting, as already 
stated, the frames are outside instead of inside of the 
wheels. 

Question 355. Now is the tender supported on the 
trucks ? 

Answer. It rests on the centre of the front truck and 
on a bearing, n, fig. 204, on the frames on each side of 
the back truck. This arrangement gives three bear- 
ing points, the advantages of which have already been 
explained. A truck which supports the load which it 
carries in the centre is said to be centre-bearing, and if 
the load is carried on each side, side-bearing. 

Question 356. How are the brakes attached to the 
tender f 



Tenders. 357 

Answer. They are attached usually to the back truck 
alone, but in some cases to both trucks, and are oper- 
ated by a wheel, N, fig. 204, and a shaft which ex- 
tends below the tender frame and on which a chain 
attached to the brakes is wound. 

Question 357. How much water and coal does an 
ordinary tender carry f 

Answer. A tender for a thirty-ton engine carries 
from 1,500 to 2,000 gallons of water and three to four 
tons of coal, and weighs from 40,000 to 45,000 pounds 
loaded. An engine of this kind and its tender there- 
fore weigh about 100,000 pounds, which, being even 
figures, can easily be remembered. 



PART XVIII. 



FKICTION AND LUBRICATION. 

Question 358. What is meant by friction ? 

Answer. Friction is the resistance between two 
bodies in contact which opposes the sliding of the 
one on the other. Thus if a brick is placed on a board 
with a slight inclination, it will not slide because the 
friction between them, or the resistance opposed to 
motion, is greater than the force exerted by the 
weight of the brick to move it downward. If, how- 
ever, the inclination of the board is increased suf- 
ficiently so that a larger proportion of the weight of 
the brick urges it downward, then the friction will be 
overcome, and it will slide. When the brake-blocks 
of a car are pressed against the wheels, they produce 
friction, which resists the revolving motion of the 
wheels and will ultimately stop the car ; and when the 
weight of an engine is supported on the driving- 
wheels and they rest on the rails, the friction between 
them, as has already been pointed out, resists their 
slipping on each other, and thus enables a locomotive 
to exert tractive force. Friction also resists the turn- 
ing of an axle on its journal and therefore makes the 
tractive force of the locomotive necessary to move a 
train of cars. 

Question 359, On what does the amount of friction 



Friction and Lubrication. 359 

Answer. The amount of friction of two bodies in 
contact depends (1) upon the pressure of the one 

ON THE OTHER, AND IS INDEPENDENT OF THE AREA 
OF THE SURFACES IN CONTACT ; (2) ON THE NATURE 
OF THE MATERIALS IN CONTACT J (3) ON THE NATURE 
OF THE SUBSTANCE, SUCH AS OIL OR OTHER LUBRI- 
CANT, WHICH IS INTERPOSED BETWEEN THEM. Thus, 

a brick will slide down an inclined board as easily if 
it is laid on its broadest side as it will if placed edge- 
wise ; and if a cast iron plate, say 10 inches square, 
is planed and scraped, so as to be as nearly a perfect 
plane surface as it is possible to make it, it will, if 
loaded with say a hundred pounds weight, slide on a 
similar true surface as easily as another plate with 
half as much area and loaded with the same weight. 
A shaft resting against a long bearing will require 
no more power to turn it than would be needed if 
the bearing was short. * 

Question 360. What is meant by the " co-efficient of 
friction ?" 

Answer. It is the proportion which the resistance to 
sliding motion bears to the force pressing the surfaces 
together. Thus a smooth, clean and dry cast iron 
plate loaded with 100 pounds will require a force of 
about 15 pounds, or fifteen one-hundredths of the 
weight or pressure of the plates, to slide them on 
each other. The co-efficient of friction is therefore said 
to be 0.15, and with any other weight or -pressure on 
the plates we could determine the force required to 
slide them on each other by multiplying the pressure 
by the co-efficient of friction. Thus, if the plates were 



* Tn fact, ordinarily less power is required to turn it if the bearing is 
long than if it is short, the reasops for which will be explained here- 
after. 



360 Catechism of the Locomotive. 

loaded with 250 pounds, the force required to slide 
the one on the other would be equal to 250 X .15= 
37.5 pounds. The co-efficient of friction, however, 
varies for different materials. Thus, while the 
co-efficient of friction between two pieces of 
smooth, clean and dry cast iron is 0.15, that of a 
piece of brass on cast iron, under similar conditions, 
is 0.22, and of two pieces of wood about 0.4. 

Question 361. What is the effect of introducing some 
unguent or lubricating material, such as oil, between the 
surfaces in contact ? 

Answer. The co-efficient of friction is very much re- 
duced thereby. Thus the co-efficient of friction of the 
cast iron plates, if their surfaces are greased with tal- 
low, is 0.1 ; if lubricated with lard 0.07, with olive oil 
0.064, and with lard and plumbago 0.055, thus show- 
ing that the amount of the friction depends very much 
upon the nature of the lubricant which is used, as 
well as on that of the materials in contact. 

Question 362. What effect on the amount of friction 
has the manner of applying the lubricating material to the 
surfaces in contact ? 

Answer. The more perfect the lubrication the less 
will be the co-efficient of friction. It has, for example, 
been found by experiments made with cast iron shafts 
turning on bearings of the same material that when 
the lubricating material was applied so that the sur- 
faces were only " unctuous," that is slightly greasy, 
the co-efficient of friction was very little less than 
when they were dry, that is when there was no lubri- 
cating substance between them, and that when they 
were greased " from time to time " the co-efficient was 
reduG«d to 0.07 and 0.08 j but when they were con- 



Friction and Lubrication. 361 

tinually oiled it averaged 0.05, and sometimes fell as 
low as 0.025, showing that with the best lubrication 
the friction was only one-sixth what it was when the 
surfaces were only " unctuous." Between these two 
limits there is every degree of frictional resistance, 
according to the condition of lubrication. This shows 
how important it is that the oiling fixtures should be 
kept in the most perfect condition and the utmost 
care be exercised in keeping every part of a locomo- 
tive thoroughly lubricated. 

Question 363. What effect does the pressure per 
square inch of the surfaces in contact have upon the 
lubrication ? 

Answer. The tendency is, when this pressure be- 
comes excessive, to press out the lubricant which is 
between the two surfaces, and ordinary experience 
proves that the greater the weight or the force per 
square inch with which two bodies are pressed to- 
gether, the greater is the difficulty of keeping them 
perfectly lubricated. 

Thus it is easier to keep the journals of a car well 
lubricated when it is empty than when it is heavily 
loaded, and the guide-bars of a locomotive are more 
liable to be cut when the engine is pulling a heavy 
load than with a light one. 

Question 364. What effect has the velocity of the sur- 
faces in contact on the friction and lubrication ? 

Answer. With the surfaces in the same condition, 
the friction is independent of the velocity of motion of 
the surfaces against each other, but perfect lubrica- 
tion becomes more difficult as the velocity increases, 
so that an increase of velocity will often increase indi- 
rectly the amount of friction. Thus, taking our pre- 
31 



362 Catechism of the Locomotive, 

vious illustrations, it is more difficult to keep the 
journals of a car or engine well lubricated when run- 
ning fast than when running slow, and the same thing 
is true of the guide-bars. 

Question 365. What considerations should govern the 
proportions of frictional bearings for locomotives and 
other machines ? 

Answer. The dimensions to be given them should 
not be determined from a consideration solely of their 
resistance to rupture, * but they should be made so 
large that the pressure they must bear will be dis- 
tributed over so much surface that the proportion 
borne by each square inch will be comparatively small, 
thus making good lubrication much less difficult, and 
consequently reducing the co-efficient of friction. 

Question 366. Is not the amount of energy required 
to overcome the friction on a journal of large diameter 
greater than would be required if the journal was 
smaller ? 

Answer. If the co-efficient of friction in the two 
cases is the same, undoubtedly the large journal will 
require the greatest expenditure of energy to turn it, 
because its periphery moves further than that of the 
small one; but the advantage attributed to large 
journals is that they can be lubricated more perfectly, 
because their surfaces being larger the pressure is not 
so great per square inch, and thus the gain from the 
reduction of the co-efficient of friction is greater than 
the loss attributable to the increase of the diameter of 
the journal. Thus if a car journal is 3J inches in 
diameter X 5J inches long, the available surface ex- 
posed to friction is equal to that of a longitudinal 



*Morin's Mechanics. 



Friction and Lubrication. 363 

section of the journal, or 3J x5^ = 17.875 square 
inches. * Supposing now that the journal is loaded 
with 5,000 pounds, and the average co-efficient of fric- 
tion is 0.085. In one revolution of the wheel the 
journal will move 0.85 of a foot, and therefore 5,000 X 
.085 =361^ foot-pounds of work. If now the journal 
is made, as has been proposed, 3f X 7 inches, then its 
effective surface will be equal to 26J square inches, 
but the journal will move 0.98 of a foot in one revolu- 
tion. If, however, the lubrication is improved by the 
increased area of the journal so that the co-efficient of 
friction is reduced from 0.085 to 0.07, then the energy 
consumed in one revolution will be equal to 5,000 X 
0.7x.98=343 foot-pounds, or less than was consumed 
with the small journals. The co-efficient of friction is 
assumed, and could only be determined by experi- 
ment, but the assumption shows how the resistance of 
the large journals may be less than that of the small 
ones. Of course it would be better to give the in- 
creased bearing surface by adding to the length of the 
journal, but nearly all locomotives and car journals 
must be increased in diameter as well as in length 
when they are enlarged, in order to have the requisite 
strength to carry the loads they must bear. 

Question 367. Is the law that friction is in pro- 
portion TO THE PRESSURE ON EACH OTHER BY THE 
surfaces of gontact true under all circumstances ? 

Answer. No ; there is a limit to the exactness of the 
above law, when the pressure becomes so intense as to 
crush or grind the parts of the bodies at and near 

• The reason for this is that the effective surface of the journal A, fig. 
209. which resists the pressure of the bearing, is equivalent only to the 
horizontal area represented by the dotted line a. b. just as the surface 
which resists the pressure inside of a boiler is equivalent to the diameter 
multiplied by its length, as was explained in answer to Question 99. 



364 Catechism of the Locomotive. 

their surfaces of contact. At and beyond that limit 
the friction increases more rapidly than the pres- 
sure j* and the friction then becomes very irregular. 

Question 368. In what cases is the limit referred to 
probably reached? 

Answer. Probably in some locomotives the pressure 
of the driving-wheels on the rails is sufficient to part- 
ly crush the latter. 

Question 369. What effect has the nature of the ma- 
terials in contact on the friction ? 

Answer. The amount of friction and also the lubri- 
cation is very much influenced by the nature of the 
bearing surface and also by the material used as a lu- 
bricant. Some metals, such as brass and other alloys, 
are much less liable to abrasion and seem to retain 
lubricants on their surfaces better than other metals, 
and are therefore much used for journal and other 
bearings. Some substances, especially oils, are good 
lubricants, while other materials of apparently similar 
nature are not. The reason why these materials pos- 
sess these properties while others are without them is 
not known, and the value of any material as a lubri- 
cant, or the degree to which another will resist fric- 
tion without abrasion, can only be tested by experi- 
ment. 



*Rankine. 



PART XIX. 
COMBUSTION. 

Question 370. Wliat is meant by combustion ? 

Answer. By combustion is meant the phenomenon 
ordinarily called burning, as when a piece of wood or 
coal or a candle is burnt. In reality combustion is a 
union of one of the " chemical elements" oxygen, of 
which the atmosphere is composed, with the elements 
which constitute the fuel. 

Question 371. What is meant by the term " chemical 
element f " 

Answer. The science of chemistry has demonstrated 
that nearly all substances by which we are surrounded 
are composed of certain other substances, which latter, 
as far as is now known, are not compounds, and are 
therefore called elementary substances, or chemical ele- 
ments. Thus the air by which we are surrounded is 
composed of two gases, called nitrogen and oxygen ; 
water is composed of hydrogen and oxygen, and 
coal chiefly of carbon and hydrogen. There are 
now over sixty of these elementary substances known. 
From no one of them have chemists been able to ex- 
tract any material excepting the substance itself. 
These elementary substances will combine with others 
so as to form what is apparently a new material, but 
on weighing it it will be found that the weight of the 
new material is greater than the original elementary 
31* 






366 Catechism of the Locomotive. 

substance, showing that something was added to it 
which effected the change.* 

Question 372. To what fact is this combination or 
combustion of elementary substances due ? 

Answer. It is owing to the fact — the exact reason 
for which is perhaps not yet understood fully — that 
the atoms of the elementary substances of which fuel 
is composed, that is hydrogen and carbon, and the 
atoms of oxygen, which forms part of the atmosphere 
by which we are surrounded, attract each other with 
great energy when they are excited into activity by 
the application of heat. 

Question 373. What phenomenon always attends 
chemical combination of substances f 

Answer. Such combination always gives out heat, 
whereas their separation absorbs heat. It has further 
been proved by actual experiment that the amount of 
heat liberated by the chemical union of the same 
quantity or number of atoms of two or more substances 
is always the same, and that when, by any cause, the 
atoms thus joined are separated, exactly the same 
amount of heat is absorbed.* 

Question 374. In what proportions do the elementary 
substances combine with each other? 

Answer. It is a law of chemistry that each of the 
elementary substanees combines with the others in 
certain definite proportions only. These proportions 
vary for the different elements, and have been deter- 
mined with great accuracy by chemists. Thus, eight 
parts by weight of oxygen will combine with nitrogen 
and form atmospheric air, or the same proportion of 
oxygen will combine with hydrogen and form water, 

• " The New Chemistry," by J. P. Cooke, Jr. 



Combustion, 367 

or with carbon and form carbonic acid, which is the 
deadly gas which accumulates at the bottom of wells. 

Now oxygen always combines with other substances 
in the proportion of eight parts by weight, or by some 
simple multiple of eight, that is 8x2=16 parts, or 
8x3=24 parts, etc. Each of the other elementary 
substances also has a certain fixed proportion in which 
it combines with others, and this proportion, which is 
usually given by weight, is represented by a number 
called its chemical equivalent. Thus 8 is the chemical 
equivalent of oxygen. Carbon combines with other 
elements in proportions of 6 and nitrogen in propor- 
tions of 14, so that 6 and 14 are the chemical equiva- 
lents of carbon and nitrogen. Now 8 parts by weight 
of oxygen can be made to combine with 14 parts of 
nitrogen, or 8x2=16 parts of oxygen will combine 
with 14 of nitrogen, but it is impossible to make, say 
12 parts of oxygen combine with 14 parts of nitrogen. 
We can combine 14x2=28 parts of nitrogen with 8 
parts of oxygen, but no chemical process can make 
say 10 or 20 parts of nitrogen combine with 8 parts of 
oxygen. If 20 parts of nitrogen are mixed with 8 
parts of oxygen, then the latter will combine with 14 
parts of the former, but 6 parts of nitrogen will be left, 
and chemical combination will then cease. 

The following table will give the chemical equiva- 
lents of the principal elements which enter into the 
process of combustion of the fuel used in locomotives : 

Chemical equiva- 
lent by weight. 

Oxygen 8 

Nitrogen 14 

Hydrogen 1 

Carbon 6 

Sulphur 16 

Question 375. What effect do the proportions in which 



368 Catechism of the Locomotive. 

elements are combined have upon the substances which are 
produced by the combination f 

Answer. A change in the proportions in which the 
elements are combined usually alters the entire nature 
of the substance, so far at least as it affects our senses. 
For instance, oxygen unites chemically with nitrogen 
in different proportions, forming five distinct sub- 
stances, each essentially different from the others, 
thus: 

14 parts ot Nitrogen with 8 of Oxygen forms Nitrous Oxide. 

14 " " «' " 16 " " " Nitric Oxide. 

14 " " " " 24 " " " Hyponitrous Acid. 

14 " « " " 32 " " " Nitrous Acid. 

14 ■■ " « " 40 " " " Nitric Acid. 

We here find the elements of the air we breathe, by 
a mere change in the proportions in which they are 
united, forming distinct substances, which differ from 
each other as much as laughing gas (nitrous oxide) does 
from that most destructive agent nitric acid, commonly 
called aqua fortis* 

Question 376. What occurs when a fresh supply of 
bituminous coal is thrown on a bright fire in the fire-box 
of a locomotive ? 

Answer. The fresh coal is first heated by the fire, 
and if a sufficient quantity is thrown in to prevent the 
immediate formation of flame,t a volume of gas or 
vapor, usually of a dark yellow or brown color, is given 
off. The quantity evolved will be greatest when the 
coal is very small. This gas or vapor is commonly 
called smoke, but it does not deposit soot and in reality 
is not true smoke. If a sheet of white paper be held 
over the vapor as it escapes from the coal and there is 



* Combustion of Coal and the Prevention of Smoke, by C. Wye Wil- 
liams. 

t Usually if more than two or three shovels full are thrown in there 
will be no immediate formation of flame. 



Combustion, 369 

no flame, the sheet will become slowly coated with a 
sticky matter of brown color difficult to remove, and 
having a strong tarry or sulphurous smell ; whereas 
if a sheet of paper is held over smoke it will quickly 
be covered with black soot. The color and smell left 
on the paper in the first case are due to the tarry 
matter, sulphur, and other ingredients in the gas. 
Deprived of the coloring matters, the vapor is a chem- 
ical mixture of 2 parts of hydrogen and 6 parts of 
carbon, and is called carburetted hydrogen, and is 
nearly the same as the colorless gas by which our 
houses are lighted.* A similar gas is generated at 
the wick of a burning candle or lamp and is consumed 
in the flame. Before the gas is expelled from the fresh 
coal the latter must be heated to a temperature of 
about 1,200 degrees, so that if 100 pounds at a tem- 
perature of 50 degrees is put on the fire 23,000 units 
of heat will be absorbed to heat the coal.f Nor is this 
all, as has been explained in answer to Question 38, 
when any substance is vaporized a certain amount of 
heat apparently disappears, which has been called the 
heat of evaporation or of gasification. Average bitu- 
minous coal contains about 80 per cent, of carbon, 5 per 
cent, of hydrogen and 15 per cent, of other substances 
usually regarded as impurities. When the coal is 
heated up to about 1,200 degrees, the 5 per cent, of 
hydrogen unites with three times its weight of carbon, 
and thus 20 per cent, of the coal is converted into the 
gas described. In this process a large amount of heat 
is absorbed or becomes latent, as it does when water or 



* A Treatise on Steam Boilers, by Robert Wilson. 

t The quantity of heat required to heat coal is only about one-fifth 
that needed to heat the same weight of water to the same temperature. 






370 Catechism of the Locomotive. 

any other substance is converted into vapor. It will 
therefore be seen that the first effect of putting fresh 
coal on the fire is to cool the fire. This fact has an im- 
portant bearing on the question of combustion and 
will be referred to hereafter. 

Question 377. How can tine process of the combustion 
of the gas generated from the coal be best explained ? 

Answer. As this gas is substantially the same as 
ordinary illuminating gas, the manner in which it 
burns can perhaps be made clearer by examining the 
combustion of an ordinary gas-light. As stated be- 
fore, combustion is a chemical union of the oxygen 
which forms one of the elements of the air with the 
hydrogen and carbon of the fuel, which, in this case, 
form gas. It should be clearly kept in mind that 
combustion is the result of this union, and that the 
oxygen is as essential to combustion as coal or gas, 
and in fact is the fuel of combustion just as much as 
coal or gas is. If we were to conduct a pipe from the 
external air into a vessel filled with coal gas we could 
light the air and it would burn in the gas as the gas 
burns in the air. 

It will be noticed, however, that before either the 
gas or the air will burn, they must be lighted. Air 
and gas, even if mixed together in the same vessel, 
will not burn unless they are lighted. This can be 
done by the flame of any burning material, or with a 
piece of metal heated to a very high temperature, or 
by an electric spark. In other words it may be said 
that the atoms of the two gases must be excited into 
activity by the application of heat, that is, what is 
called an igniting temperature must be communicated 
to them before chemical combination will begin. The 



Combustion. 371 

chief feature which distinguishes combustion from 
other chemical union is the circumstance that the heat 
generated during the combination is sufficient to 
maintain an igniting temperature, and the necessity 
of doing so in order to continue the process is of very 
great importance in the combustion of coal in locomo- 
tive boilers, as will be shown hereafter. 

Question 378. How does an ordinary gas-light burn 
after it is lighted f 

Answer. Under ordinary conditions the hydrogen, 
which is the most combustible of the two elements of 
which coal gas is formed, is the first to burn. This 
part of the combustion forms the lower bluish part of 
the flame. The combustion of the hydrogen thus 
separates it from the carbon, which is then set free ; 
and as carbon is never found in a gaseous condition 
when uncombined with other substances, it at once 
assumes the form of fine soot when the hydrogen is 
burned away from it. This fine soot, or pulverized 
carbon, is, however, intensely heated by the combus- 
tion of the hydrogen. Now carbon when heated to an 
igniting temperature will, if brought into contact with 
a sufficient quantity of oxygen, combine with it or be 
burned. Each particle of carbon thus becomes a 
glowing centre of radiation, throwing out its luminous 
rays in every direction. The sparks last, however, 
but an instant, for the next moment they are con- 
sumed by the oxygen which is aroused to full activity 
by the heat, and only a transparent gas rises from the 
flame. But the same process continues ; other parti- 
cles succeed, which become heated and ignited in their 
turn, and it is to this combustion of the solid particles 



B72 



Catechism of the Locomotive, 



of carbon that the light which is given out by a 
burner or candle is due.* 

Question 379. Why does a gas-burner, candle or other 
flame sometimes smoke ? 

Answer. Because the supply of oxygen is then in- 
sufficient to consume the particles of solid carbon 
*vhich are set free and which then assume the form ci 




soot. This can be illustrated if we cut a hole in a 
card, d d, fig. 210, so as to fit over an ordinary gas- 
burner, b. If we then light the gas and place a glass 
chimney, a a, over the burner and let it rest on the 
card, it will be found that the flame will at once begia 

" «« The New Chemist**" ^ J. P. Cooke, 0*. 



Combustion. 373 

to smoke, because very little air can then come in con- 
tact with the flame, and therefore when the fine par- 
ticles of carbon are set free by the combustion of the 
hydrogen, instead of being burned as they would be 
if the air with its supply of oxygen were not excluded 
from the flame by the chimney, they escape uncon- 
sumed in the form of fine black powder or soot. If 
we raise the chimney up from the card, as shown in 
fig. 211, so as to leave enough space between them at 
the bottom of the chimney to permit air to enter so as 
to supply the flame with oxygen, the smoke will in- 
stantly cease, as the particles of carbon are then con- 
sumed. The same principle is illustrated in an ordi- 
nary kerosene lamp. It is well known that without 
a chimney the flames of nearly all such lamps smoke 
intolerably, whereas with a glass chimney and the pe- 
culiarly formed deflector which surrounds the wick 
the light burns without smoke unless the wick is turned 
up high. The effect of the chimney is to produce a 
draft, which is thrown against the flame by the de- 
flector, and thus a sufficient supply of oxygen is fur- 
nished to consume all the particles of carbon, whereas 
without the draft produced by the chimney the supply 
01 oxygen is insufficient to ignite all the carbon, which 
then escapes in the form of smoke or soot. 

It must not, however, be hastily assumed that if the 
flame does not give out a bright light, therefore the 
combustion is not complete. As has already been 
stated, the light of the gas flame is due to the pres- 
ence of burning particles of solid carbon, which is set 
free by the combustion of the hydrogen with which it 
is combined. After it is separated from the hydrogen 
it immediately assumaa a solid form. If the coal gas 
32 



374 



Catechism of the Locomotive, 



is mixed with a sufficient quantity of air before it is 
burned, the oxygen in the latter will be in such inti- 
mate contact with the former that the difference of 
affinity of oxygen for the carbon and hydrogen does 
not come into play, and as there is enough oxygen for 
all, the carbon is burnt before it is set free, and as 
there are then no solid particles in the flame, there is 
no light. This is illustrated by a "Bunsen burner," 
fig. 212, which is much used in chemical laboratories. 




ft consists of a small tube or burner, a, which is placed 
inside of another larger tube b. The latter has holes, 
o, c, a little below the top of the small tube. The 
surrent of gas escaping from the small tube produces 
what is called an induced current of air in the large 
tube. This air enters through the holes c, c, and is 



Combustion. 375 

mixed with the gas in the tube b, and the mixture is 
burned at d. The flame from such a burner gives 
hardly any light, but the heat is intense, as is shown 
if a metal wire is held in it for a few seconds, as if 
will very soon glow with heat. 

Question 380. What important difference is there in 
the structure of the flame of a Bunsen burner and that of 
an ordinary gas-burner or candle f 

Answer. The gas which escapes from the mouth doi 
the pipe b, fig. 212, is mixed with air, and therefore 
contains v/ithin itself the elements which only need 
to combine to produce combustion ; whereas with an 
ordinary gas-burner or candle the air comes in contact 
with the flame only from the outside, or on its surface. 
This is shown better perhaps in the flame of an ordi- 
nary candle. The heat of such a flame distils a gas 
from the melted tallow, which is similar in nature to 
that which escapes from coal at a high temperature. 
Now by observing the candle very closely it will be 
seen that at the bottom close to the wick there is very 
little combustion, as the gas there first escapes from 
the wick and is not heated to a sufficiently high tem- 
perature to burn freely. A little above the lowermost 
part the flame is of a pale bluish color, which is due 
to the combustion of the hydrogen. Above that, 
where the carbon is set free, its particles glow with 
heat imparted by the burning hydrogen and are then 
consumed by uniting with the oxygen of the air. The 
combustion occurs only at the surface of the flame, 
the inside being a mass of combustible gas which can- 
not burn until it in turn comes in contact with the 
oxygen of the air. This can be proved by inserting 
onQ end of a small tube, fig. 213 (a pipe stem will do), 



376 Catechism of the Locomotive, 

which is open at both ends, into the name. The com- 
bustible gas will then escape at the other end and can 
easily be lighted with a match. 

It will be found that the name from the Bunsen 
burner is much more intense than that of an ordinary 
candle or gas-burner. The reason of this is that com- 
bustion, as already stated, takes place through the 
whole mass of its flame, whereas an ordinary flame 
burns only at its surface. Common gas-jets are there- 
fore arranged so that the flames will be flat, thus ex- 
posing as much surface to the air as possible, and, as 
explained in answer to Question 329, in describing 
the lamps for head-lights, their burners are usually 
made with a circular wick, through the centre of 
which a current of air circulates. This arrangement 
exposes a larger surface of the flame to the air, and 
also with the aid of a chimney furnishes an abundant 
supply for combustion. In stationary boilers with 
long flues of a large sectional area the flame will 
often extend for thirty feet, showing that while com- 
bustion is going on only at the surface of the flame, 
it takes a long time to complete the process. The 
same thing is shown if a gas-burner is made with a 
single round hole. The flame will then be very long 
and liable to smoke at the top. 

Question 381. From the preceding considerations 
what may we infer to be necessary in order to consume coal 
gas perfectly ? 

Answer. In the first jDlace, that there must exist a cer- 
tain degree of what chemists call " molecular activity," 
which is produced by heat, or what we have called the 
igniting temperature. The necessity of this is suffi- 
ciently obvious with ordinary gas-burners, as they 



Combustion. 377 

must always be lighted before they will burn. Now im- 
agine that it was required to burn gas which was issu- 
ing from a hundred jets, of every variety of size, in a 
violent wind storm, or gusts of wind. Obviously it 
would be necessary to keep a lighted torch all the time 
to relight those which would be blown out. The gas 
in a locomotive fire-box is in reality burnt in a storm 
of wind more violent than any natural one. It is 
therefore necessary to be constantly ready to relight 
the streams of gas which the faintest breath would 
extinguish, or those of larger volume which have ab- 
sorbed a great deal of heat and thus reduced the tem- 
perature at the time and place of their birth, when they 
assumed the gaseous form, as was explained in answer 
to Question 376. To relight them with certainty it is 
necessary to keep a constant temperature in the fire- 
box high enough to ignite the gas which escapes or is 
distilled from the coal. 

Second. That the chemical change in combustion 
consists simply in the union of the elements burned 
with the oxygen of the air ; and therefore, to burn the 
gas perfectly, without smoke or waste, enough air must 
be furnished to supply all the oxygen which will com- 
bine with the fuel. 

Third. That the air must be mixed with the gas, 
otherwise combustion will occur only at the surface 
of the flame, and will therefore be so slow that much 
of the gas will escape unconsumed. 

It must be clearly kept in mind that no one or two 
of these requirements alone, without the third, will 
burn coal perfectly. What is needed is all three in 
combination. A very common error is to suppose that 
passing smoke over a hot fire, or in other words, main- 
32*- 



378 Catechism of the Locomotive, 

taining an igniting temperature, will alone effect per- 
fect combustion ; or that if a sufficient supply of air 
is admitted, without an igniting temperature in the fire- 
box, the fuel will be burnt completely. Neither of them 
will accomplish the, object alone, and the gas and air 
must at the same time be thoroughly mixed with the 
burning gas in the fire-box. 

Question 382. What substances are produced by the 
combustion of coal gas ? 

Answer. The hydrogen of coal gas unites during 
combustion with oxygen in the proportion, as indica- 
ted by their chemical equivalents, of 1 part by weight 
of hydrogen with 8 parts of oxygen, the product of 
which is water. Of course at the high temperature 
at which the gases combine or burn the water is pro- 
duced in the form of steam. That water or steam is one 
of the products of combustion is shown every cold even- 
ing, when the insides of shop show-windows are covered 
with moisture, which is due to the steam that is given 
off by the burning gas-lights or lamps inside, and is 
then condensed against the cold glass. 

Carbon combines with oxygen in two proportions: 
first, 6 parts of the former will unite with 8 of the 
latter, forming what is called carbonic oxide ; or 6 parts 
of carbon will combine with 16 parts of oxygen, form- 
ing carbonic acid gas or carbonic dioxide, as it is called 
in some of the new books on chemistry. It is proba- 
ble that the former compound, that is carbonic oxide, 
is never or very rarely formed in the flame of coal gas ; 
but, as will be seen hereafter, is a very common and 
wasteful product of the combustion of the solid portion 
of the coal which is left after the gas is expelled from 
it. When there is not enough oxygen for the perfect 



Combustion. 379 

combustion of the carbon in the flame, it smokes, and 
the carbon escapes in the form of soot. This, as will 
be shown, may in a locomotive fire-box help to form 
carbonic oxide after it leaves the flame. 

Question 383. What remains in the coal after all the 
gas is expelled by heat ? 

Answer. What remains is ordinarily called coke, 
which, with the exception of some incombustible sub- 
stances, such as sand, ashes and cinders, which the coal 
contains, is nearly pure carbon. 

Question 384. What is the chemical process of the 
combustion of coke ? 

Answer. The solid carbon of the coke when raised 
to an igniting temperature; or, in other words, on 
being lighted, unites with the oxygen in one of the two 
proportions already given ; that is, if the supply of oxy- 
gen is sufficient, 6 parts of the carbon of the coke 
unite with 16 parts of oxygen, forming carbonic acid 
gas, or carbonic dioxide. If, however, the layer of 
fuel on the grates is thick, or the supply of air is com- 
paratively small, there will not be enough oxygen to 
supply 16 parts of the latter to each 6 parts of the 
carbon, so that when that occurs, instead of combin- 
ing in that proportion, and thus forming carbonic 
dioxide, 8 parts of oxygen will unite with 6 parts of 
carbon and form carbonic oxide. Now it should be 
carefully kept in mind that the heat of combustion is 
due to the union, or, as it is sometimes expressed, it is 
the clashing together of the molecules of the two ele- 
ments which unite. If, therefore, only half the quan- 
tity of oxygen unites with 6 parts of carbon, evi- 
dently there will be less heat evolved than there would 
be if twice that amount of oxygen combined with the 



380 Catechism of the Locomotive, 

carbon. Prom carefully made experiments it was 
found that the total heat of the combustion of one 
pound of carbon when converted into carbonic oxide 
was 4,400 units, whereas when it was converted into 
carbonic dioxide 14,500 units were given out, It will 
thus be seen that it is extremely wasteful to burn coal 
without a sufficient supply of air to produce carbonic 
dioxide. The danger of waste from this cause is also 
increased by the fact that carbonic oxide is colorless 
and odorless, and therefore its production is not appar- 
ent, especially as most persons have the impression 
that when there is no smoke from a fire combustion is 
then complete. It burns with a blue or yellowish flame 
when air is admitted into the fire-box, and its presence 
can often be detected by these phenomena when the 
furnace door is opened. 

Question 385. How can the requisite quantity of air 
be supplied to the fire in a locomotive fire-box f 

Answer. It is done in two ways : one is to keep but 
little coal on the grates, or in the phraseology of fire- 
men, to "carry a light fire." The other method is to 
admit fresh air above the fire. If the latter plan is 
adopted when the supply of air through the grates is 
insufficient for perfect combustion, the carbonic oxide 
will unite with the oxygen of the air above the fire, 
and thus a second combustion will take place, the 
product of which will be carbonic dioxide. It must 
be kept in mind, however, that not only must there be 
enough air supplied to the fire to consume the coke, 
but the gases which are distilled from the coal must 
also be supplied with oxygen in order to effect their 
perfect combustion. Even if enough air is admitted 
to consume the coke perfectly, if the carbonic dioxide 



Combustion, 381 

thus formed is mixed with large quantities of smoke 
above the fire, the solid carbon or soot of the smoke 
may then combine with the dioxide and thus form car- 
bonic oxide, if there is not enough fresh air present to 
furnish the requisite oxygen for the carbon in the 
smoke. A very common error is to suppose that smoke 
can be burned by passing it over or through a very 
hot fire. The smoke may thus be made invisible, it 
is true, but it does not therefore follow that it is per- 
fectly consumed. 

Question 386. Is it possible to admit too much air 
into the fire-box of a locomotive^ 

Answer. Yes ; probably all the air that is admitted 
which is not necessary for combustion, or, in other 
words, the oxygen of which does not combine with the 
fuel, instead of increasing diminishes the amount of 
water converted into steam. It does this in two 
ways ; first, by reducing the temperature of the gases 
in contact with the heating surfaces, and second, by 
increasing the volume or quantity of the gases which 
must pass through the tubes. Heat is transmitted 
through the heating surface of a boiler in proportion 
to the difference of the temperature of the products of 
combustion on one side and the water on the other.* 
Thus, if the temperature of the water on one side 
is 250 degrees, and the hot gases on the other is 500, 
there will be only half as much heat transmitted to 
the water in a given time as there would be if the 
gases had a temperature of 750 degrees. If the vol- 
ume of gases is doubled by the admission of too much 
air, then obviously in order to pass through the tubes 

ourp^UllusfrrUoT n0t absol ^y «<>rrect, but is near enough for 



182 Catechism of the Locomotive. 

they must move at double the velocity, so that not 
only is their temperature diminished, but the time 
they are in contact with the heating surface is dimin- 
ished in like proportion. This is shown by the effect 
of opening the furnace door, or of allowing the fire to 
burn away so that portions of the grate are left un- 
covered. The volume of cold air which will in either 
of these cases enter the fire-box will be so great that 
the pressure of the steam in the boiler will begin to 
fall at once. 

Question 387. What determines the amount of air 
which must be admitted to the fire-box of a locomotive to 
effect perfect combustion ? 

Answer. This depends chiefly upon the rate of com- 
bustion, that is, the number of pounds of coal con- 
sumed per hour on each square foot of grate surface. 
Of course if 100 pounds is burnt it will require twice 
the supply of air that would be needed if only 50 
pounds were burnt. 

Question 388. How should the air be admitted so as 
to burn the coal perfectly ? 

Answer. In burning bituminous coal it has been 
shown that there are two distinct bodies to be dealt 
with, the one coke, a solid, the other coal gas, which is 
of course a gaseous body. The combustion of each of 
these is necessarily a distinct process. If the requi- 
site quantity of air is supplied to the burning coke, or 
solid portion of the coal, it will, as has been shown, 
be converted into carbonic dioxide, and thus be per- 
fectly consumed. If the supply of air is insufficient, 
the product of the combustion will be carbonic oxide, 
which is very wasteful. If, for example, there is a 
thick layer of coke on the grate, the air will enter and 



Combustion. 383 

unite with the lower layer of coal and form carbonic 
dioxide, but as it rises there will not be enough air to 
supply oxygen to the carbon, and another equivalent 
of the latter will therefore combine with the carbonic 
dioxide and form carbonic oxide. It is evident, 
though, that the thinner the fire, the easier it is for 
air to pass through it, and consequently the greater 
will be the quantity which will enter the fire-box. 
Nothing would seem easier then than to regulate the 
thickness of the fire on the grates so that just the 
needed amount of air would pass through it. If coke 
alone was to be burned, undoubtedly very perfect com- 
bustion would be (and has been) effected in this way, 
but if a charge of fresh coal, say 100 pounds, is thrown 
on the fire, the coal gas is very soon generated and es- 
capes into the fire-box. This gas needs an additional 
amount of air for its combustion. It would seem that 
this could be supplied by reducing the thickness of 
the fire still further, so that more air would pass 
through it than was needed for the combustion of the 
coke alone. If this was done then too much air would 
pass through the coke after the gases had all escaped 
from the fresh coal and were burned. Besides, the 
passage of the air would be the most restricted after 
the fresh charge had been put on the fire, just at the 
time when the most is needed. This difficulty might 
be overcome if a constant supply of fresh coal just 
equal to that consumed were kept on the fire all the 
time, and the thickness of fuel on the grates was then 
regulated so as to admit just air enough for the com- 
bustion of the coke and also that of the gases, the 
production of which would then be uniform. An ap- 
proximation to this method of feeding the fire is, in 



884 Catechism of the Locomotive, 

fact, what is aimed at on most locomotives, and proba- 
bly the best practical results are produced by that 
method. 

Two difficulties are, however, encountered in this 
method. In the first place it is impossible to feed a 
fire continuously with a shovel. There will be inter- 
vals between the charges which are thrown in, so that 
the supply is not uniform, even if the charges do not 
consist of more than a portion of a shovel-full at a 
time ; and if the fire was fed in this way as uniformly 
as possible it would then be necessary to open the fur- 
nace door every time fresh coal was put on the fire, 
and so much cold air would thus be admitted that 
more would be lost by lowering the temperature of the 
boiler than would be gained by the improved combus- 
tion. 

Another difficulty also is encountered in this method 
of burning coal in locomotives. In order to admit enough 
air through the fire it is necessary to keep the latter so 
thin on the grates that the violent draft produced by 
the blast lifts the coal from the grate-bars and carries 
the lighter particles through the flues unconsumed. 
It is thus extremely difficult to keep the grate uni- 
formly covered with coal, and if it is not, the air will 
enter in irregular and rapid streams or masses through 
the uncovered parts, and at the very time when it 
should be there most restricted. Such a state of things 
at once bids defiance to all regulation or control, so 
that it is found almost uniformly that firemen of loco- 
motives keep enough coal on the grates to avoid the 
danger of "losing their fire," as they express it; that 
is, having all the burning coal drawn through the 
tubes by the blast. Now, on the control of the supply 



Combustion* 385 

of air depends all that human skill can do in effecting 
perfect combustion and economy ; and unless the supply 
of fuel and the quantity on the bars can be regulated, 
it will be impossible to control the admission of the 
air.* 

Another method of feeding locomotive boilers is to 
pile up the coal in the back part in a thick layer and 
slope it downward towards the front, so that there is a 
comparatively thin fire in front. The mass piled up 
at the door becomes converted into coke, and the pro- 
duction of gas from the coal is more gradual and uni- 
form than it is when only a small quantity is thrown 
in at a time, and therefore a more uniform supply of 
air is needed for its combustion. But it is apparent 
that very little air can pass through the thick heap of 
coal at the back part of the fire-box, and that there- 
fore all, or nearly all the air which enters it must 
come in through a comparatively small portion of the 
grate. It will of course be difficult to admit the 
requisite quantity, for the reasons already stated. 

It is consequently apparent that it is practically im- 
possible to admit enough air through the grates to 
effect a constantly perfect combustion of bituminous 
coal. It is, therefore, necessary to admit a portion of 
the air above the fire. In doing this, however, in or- 
der to effect perfect combustion the air thus admitted 
must be thoroughly mixed with the gases, and in order 
to be able to enter into chemical combination, or in 
other words, to burn, the gases must combine with the 
air at an igniting temperature. If too much air is 
admitted, it will reduce the temperature in the fire- 
box so much that the gases will not ignite ; or, if it is 



* The Combustion of Coal, by C. Wye Williams. 

33 



386 Catechism of the Locomotive, 

admitted in strong currents, the air and the gases will 
flow side by side like the currents of two streams of 
water, the one muddy and the other clear, which, as 
is well known, mingle very slowly. Besides, if a hot 
stream of gas encounters a strong stream of cold air 
and comes in contact with it only at its surface, the 
latter will be cooled down below the igniting temper- 
ature ; whereas if the two had been intimately mixed 
in the right proportion, the whole mixture would have 
been hot enough to burn. It is therefore of the ut- 
most importance that the air which is admitted above 
the fire should enter the fire-box in many small jets. 
None of the openings for its admission should exceed 
J inch in diameter. With the violent draft in a loco- 
motive fire-box there is an extremely brief period of 
time for chemical combination to take place after the 
gases are expelled from the coal and before they are 
hurried into the tubes. As the chemical action be- 
tween the gases and the oxygen can only take place 
when the two are in intimate contact, too much pains 
cannot be taken to distribute the currents of admitted 
air and thus mix them with the combustible gases. 
In many cases means are adopted to delay the air and 
the gases in the fire-box so as to give them time for 
chemical combination or combustion before entering 
the tubes. 

Question 389. Does any combustion take place after 
the gases enter the tubes ? 

Answer. Very little ; as the flames are extinguished 
soon after they enter. 

Question 390. Why are the flames extinguished i ■ 
the tubes? 

Answer. They are then in contact with large quan- 



Combustion. 387 

titles of incombustible gas and beyond the reach of a 
supply of air ; besides, the temperature of the tubes 
which are surrounded with water is so low that the 
flame is soon cooled down below an igniting tempera- 
ture. 

Question 391. What temperature is necessary to ignite 
coal gas or produce flame ? 

Answer. A temperature considerably hotter than red- 
hot iron is needed, as can easily be shown by the fact 
that a gas-light can not be ignited with a red-hot poker. 

Question 392. Are there any parts of the firebox 
where the temperature is probably below the igniting 
point ? 

Answer. Yes ; along the sides and ends near the 
plates, which are covered with water on the opposite 
side. At these points the coal is usually " dead " or 
incandescent, as it remains at too low a temperature 
to burn. For this reason, in some cases a space of 
from 8 to 12 inches on each side and still more at the 
ends of the grates, is made of solid plates, without any 
openings, and therefore called " dead-grates ," so that 
no cold air can enter at those points. These plates 
are made sloping downwards from the sides towards 
the centre of the fire-box, so that the coal which falls 
on them and is thus coked, can easily be raked towards 
thte middle of the fire. This arrangement of dead 
plates often improves the combustion and results in 
greater economy of fuel. The reduction of the area of 
the openings between the grate-bars can usually be 
compensated by making the bars narrower or the 
spaces between them wider. 

Question 393. What should be the condition of the 
coal when it is put on the fire ? 



388 Catechism of the Locomotive. 

Answer. It is true of the coal as well as of the gases 
that the chemical action between it and the oxygen 
can only take place when the two are in intimate 
contact, and therefore the rapidity and completeness 
of combustion and intensity of heat will be increased 
by increasing the number of points of contact, or by 
reducing the size of the fuel. The coal should there- 
fore be broken up, but not so small as to fall between 
the grate-bars or be carried out of the fire-box by 
the blast. 

Question 394. What amount of air must be admitted 
to the fire to effect perfect combustion ? 

Answer. It was stated that average bituminous coal 
contains about 80 per cent, carbon, 5 per cent, of hy- 
drogen and 15 per cent, of other substances. As a 
large proportion of the latter are incombustible, we 
will confine ourselves for the present to the consider- 
ation of the combustion of the hydrogen and carbon 
alone. 

The hydrogen, as has been explained, unites with 
oxygen in the proportion by weight of 1 part of the 
former to 8 parts of the latter, and the product of this 
union is water, or steam. As 36 parts of air contain 
only 8 of oxygen, in order to burn the hydrogen 

IT MUST BE SUPPLIED WITH 36 TIMES ITS WEIGHT OF 
AIR. 

In order to burn the carbon perfectly it must, as 
has been explained, be converted into carbonic dioxide, 
which consists of 6 parts of carbon and 16 of oxygen; 
and as air consists of 28 parts of nitrogen to every 8 
of oxygen, we must furnish 72 parts of air to every 6 
of carbon, or, in other words, carbon needs 12 times 

ITS WEIGHT OF AIR FOR ITS PERFECT COMBUSTION. 



Combustion. 389 

Every pound of average bituminous coal therefore 
requires 1.8 lbs. of air to burn its hydrogen, and 9.6 
lbs. for the carbon, or 11.4 for both. As a portion of 
the other substances of which coal is composed, besides 
the oxygen and hydrogen, which others have been 
classed as impurities, are combustible, there will be no 
material error if we estimate the amount of air re- 
quired for the combustion of bituminous coal at 12 
pounds per pound of FUEL. As each cubic foot of 
air weighs 0.08072 lb., 12 pounds will be equal to 

= 148.6 cubic feet of air, 

0.08072 

or for the sake of even figures and a quantity which 
can easily be remembered, we will say 150 cubic feet 

OF AIR ARE NEEDED FOR THE COMBUSTION OF EACH 

pound of coab. This is the theoretical quantity of 
air which is needed for combustion. Now, unfortu- 
nately, the process of combustion in the fire-boxes of 
locomotives is one in which any very exact combina- 
tion of the substances which unite is not possible with 
the appliances which are now employed. If, therefore, 
we admitted the exact amount of air given above, 
while some portions of the fire where combustion was 
not very active might have more air than is needed, 
other portions would have too little ; and if the air is 
not very thoroughly mixed, the flame and burning 
coal may be surrounded with the products of com- 
bustion, which would exclude the air and thus reduce 
its effect upon the lire. For this reason, besides the 
air required to furnish the oxygen necessary for the 
complete combustion of the fuel, it is also necessary 
to furnish an additional quantity of air for the dilution 
33* 



390 Catechism of the Locomotive, 

of the gaseous products of combustion, which would 
otherwise prevent the free access of air to the fuel. 
The more minute the division and the greater the 
velocity with which the air rushes among the fuel, the 
smaller is the additional quantity of air required for 
dilution. In locomotive boilers, although this quan- 
tity has not been exactly ascertained, there is reason 
to believe that it may on an average be estimated at 
about one half of the air required for combustion.* 
We would therefore have as the quantity of air needed 
for combustion 

150 
150-| — 225 cubic feet. 

z 

This estimate is roughly made, but it is the nearest 
approximation at present attainable. It is probable 
that the supply of air required for dilution varies con- 
siderably in different arrangements of the fire-box and 
for different kinds of fuel, and it is possible that by 
admitting the air for combustion in small enough jets, 
and deflecting the currents of smoke and gases so as 
to cause them to mingle with the air, the quantity re- 
quired for dilution might be reduced below that indi- 
cated by the above calculation. Undoubtedly all the 
air which is admitted into the fire-box which does not 
combine with the chemical elements of the fuel lessens 
the amount of steam generated in the boiler, both with 
reference to time, that is to say per minute, and to 
fuel, that is per pound of coal consumed. But with 
the present locomotive boiler it is simply a choice of 
two evils. If no more air is admitted than theory in- 
dicates to be needed for combustion, then, owing to 



•Kankina 



Combustion, 391 

the imperfect means which are usually employed to 
cause the air and fuel to combine, a portion of the lat- 
ter will escape unconsumed j and if more air is admit- 
ted, the temperature of the products of combustion is 
lowered and their volume increased, the evils of which 
have already been pointed out. It therefore becomes 
a matter in which we are obliged to consult experi- 
ence and determine by experiment what amount of air 
it is necessary to admit to the fuel to produce the most 
economical results. 

Question 395. What proportion of the air should he 
admitted through the grate, and how much above the fire? 

Answer. This, too, is a question which can probably 
be answered best by consulting experience. The rel- 
ative quantity of air required above and below the fire 
depends very much on the nature of the fuel. Coal 
which "runs together " or cakes very much or has a 
great deal of clinker in it, doubtless, will need more air 
above the fire than other coal which is said to be 
" dryer," for the reason that it will be found impossi- 
ble to admit so much air through the caking coal in 
the grate as through the other kind. An idea of the 
relative quantity which should be admitted above and 
below the fire may be found if we know how much air 
is needed to burn the solid carbon or coke which is 
left after the gas is expelled from it, and how much 
for the gas itself. The gas which is expelled from a 
pound of coal consists of about 0.05 lb. of hydrogen 
and 0.15 lb. of carbon. Now, it has been shown that 
hydrogen requires 36 times its weight of air to burn 
it perfectly, so that 0.05 lb. would need 0.05 X 36 = 
1.8 lbs. ; and carbon requires 12 times its weight of 
air, so that for 0.15 lb. of carbon 0.15 X 12 = 1.8 lbs. 



392 Catechism of the Locomotive. 

is needed, so that for both 3.6 lbs. of air is required 
for perfect combustion. As has been shown, 12 lbs. is 
needed to consume the whole of the fuel, so that 30 
per cent, of the whole supply is required for the com- 
bustion of the gas alone. If this is diluted in the 
same proportion as that required for the combustion 
of the carbon, and it probably should be even more 
so, we would have 30 per cent, of 225 = 67.5 cubic 
feet of air required for the combustion of the gas. It 
is certain, however, that the solid coke on the grates is 
not perfectly consumed, or, in other words, converted 
into carbonic dioxide, especially when the layer of 
it on the grates is very thick. When this is the case 
the air coming in contact with the lower layer of coke 
forms carbonic dioxide, but as it rises through the 
burning coke another equivalent of carbon unites 
with the carbonic dioxide, and thus forms carbonic 
oxide. If, now, enough air is admitted above the fire, 
this carbonic oxide will combine with it, and, as has 
been explained before, a second combustion will take 
place if there is time and opportunity for combination 
before the gases enter the flues. It is therefore prob- 
able that more than 30 per cent, of the whole supply 
of air should be admitted above the fire. It is at any 
rate best to provide the means for admitting more, and 
also appliances for regulating the supply, so that it can 
be governed as experience may indicate to be best. 

Question 396. Is it not possible by enlarging the grate 
to admit enough air to the fire to 'produce perfect com- 
bustion ? 

Answer. Yes; when no air is admitted above the 
fire, large grates are found to produce the best combus- 
tion. But while it is true that the same amount of 



Combustion, 393 

heat will be produced by the union of each equivalent 
of oxygen and fuel, yet if we can force more air and 
fuel to unite in the same place, a higher temperature 
is produced in that place, just as a fire in a blacksmith's 
forge is hotter because of the forced blast than that in 
an ordinary stove, or a smelting furnace than a parlor 
grate. If, then, we can concentrate the draft in the fire 
of a locomotive, we secure a greater intensity of combus- 
tion ; and when the air is urged against the solid carbon 
with considerable force, it comes in contact with every 
point of its surface, and therefore less dilution of the air 
is needed, and consequently the products of combus- 
tion have a higher temperature ; and, as has been ex- 
plained, a larger proportion of the heat is then trans- 
ferred to the water than if the temperature is lower 
and the volume greater. 

Intensity of combustion also has the effect of main- 
taining an igniting temperature ; whereas, if the same 
amount of fuel is burned slowly, its heat may not be 
high enough to ignite the gases as they are produced. 

It is desirable, however, to have all the space that 
is possible in the fire-box, so as to give room for the 
mixing of the gases; but with a large fire-box and 
large grate a decided improvement and economy will 
often result by diminishing the effective area of the 
grate by covering a part of it with dead plates, but at 
the same time making provision for the admission of 
air above the fire. 

Question 397. What is meant by the " Total Heat 
of Combustion ? " 

Answer. It is the number of units of heat given out 
by the combustion of a given quantity (usually a pound) 
of fuel. 



394 Catechism of the Locomotive, 

Question 398. How is this determined ? 

Answer. The heat given out by the combustion of 
one pound of the chemical elements of which coal is 
composed has been determined by experiment, and 
from such data, knowing the substances of which fuel 
is composed, we can determine the amount of heat 
which would be developed if they were each perfectly 
consumed. Thus the total heat of combustion of one 
pound of hydrogen is 62,032 units, and of the same 
quantity of carbon 14,500 units.* Therefore, if a 
pound of coal contains 5 per cent, of hydrogen, the 
heat given out by the combustion of that element will 
be 62,032x0.05=3,101.60 units, and if it has 80 per 
cent, of carbon, the combustion of the latter would de- 
velop 14,500x0.80=11,600 units, so that the total 
heat of the combustion of these two elements would be 
3,101.6+11,600=14,701.6 units. It was shown in 
answer to Question 40 that it required 1,213.4 units 
of heat to convert water at zero to steam of 100 pounds 
pressure. As steam is usually generated from water 
at a temperature of about 60 degrees, the total heat 
required to convert it into steam of 100 pounds pressure 
would be 1,213.4—60=1,153.4 units. A pound of 
average bituminous coal, therefore, contains heat 
enough to convert 12J lbs. of water into steam of 
100 lbs. absolute pressure. Ordinarily only about half 
that amount of water is evaporated in locomotive 
boilers per pound of fuel. 

Question 399. What are the chief causes of this waste 
of heat ? 

Answer. It is due, first, to the waste of unburnt fuel 



* The experiments which have been made to determine these amounts 
do not agree exactly, but those given are thought to be the most trust- 
worthy. 



Combustion, 895 

in the solid state. This occurs when fuel which is 
very fine falls through the grates, or is carried through 
the tubes and out of the stack in the form of cinders.* 

Second, to the waste of unburnt fuel in the gaseous 
or smoky state. The method of preventing this waste 
by a sufiicient supply and proper distribution of air has 
been explained in the answer to preceding questions. 

Third, to the waste or loss of heat in the hot gases 
which escape up the chimney or smoke stack. The 
temperature of the fire in a locomotive fire-box in a 
state of active combustion is probably from 3,000 to 
4,000 degrees. This heat is in part radiated and con- 
ducted to the heating surface of the fire-box, and it is 
found that more water is evaporated by this portion 
of the heating surface in proportion to its area than 
by any other in the boiler. The gases when they 
enter the tubes transmit a portion of their heat to the 
surfaces with which they are first in contact. The 
amount of heat thus transmitted, as has been stated, 
is in proportion to the difference in temperature of the 
gases inside the tubes and that of the water outside. 
After passing over the part of the tube with which 
the gases are first in contact, they then arrive at an- 
other portion of the tube surface with a diminished 
temperature, and the rate of conduction is therefore di- 
minished ; so that each successive equal portion of the 
heating surface transmits a less and less quantity of 
heat, until the hot air at last leaves the heating sur- 
face and escapes up the chimney with a certain re- 
maining excess of temperature above that of the water 
in the boiler, the heat corresponding to which excess 

* It should be remarked here that some and perhaps most of the cin- 
ders which are carried out of the stack are not combustible but are torn, 
posed of the same materials that form clinkers on the grate. 



396 Catechism of the Locomotive. 

is wasted.* It is, therefore, desirable to extract as 
much heat as possible from the gases before they es- 
cape from the tubes. Now it will be impossible to 
heat the water outside of the tubes hotter than the 
gases inside. When the temperature of the water is 
equal to that of the gases, no more heat will be trans- 
mitted from one to the other. If the temperature of 
the water is 350 degrees, that of the gases in the tubes 
will never be any lower, but will escape into the 
smoke-box with not less than that amount of heat. 
If, however, the cold water is introduced at the front 
end of the tubes, so that the surface with which the 
gases are last in contact has a temperature considera- 
bly lower than 350, then an additional amount of heat 
will be transmitted before they escape. It is, there- 
fore, important that the cold feed-water should be ad- 
mitted near the front end of the boiler, so that the 
products of combustion will be in contact with the 
coldest part of the heating surface last, and thus give 
out as much of their heat as possible before they es- 
cape. As a matter of fact, the gases escape at a much 
higher temperature. Experiments made by the writer 
showed that the temperature in the smoke-box of a 
locomotive when first starting was 270 degrees, and 
when working at its maximum capacity on a steep 
grade and with a heavy train it was as high as 675 
degrees. The average temperature while running was, 
in three trials on different parts of the road, as fol- 
lows : 

Average steam pressure, 98.8 lbs. ; average temperature, 499.8 lb=>. 
Average steam pressure, 106 lbs. ; average temperature, 535.1 lbs. 
Average steam pressure, 112.2 lbs. ; average temperature, 554 lbs. 

In making these experiments a record was made of 

♦Bankiue. 



Combustion, 397 

the indications of a pyrometer and of the steam gauge 
once every minute while the engine was running. The 
distance run was 19 miles for the first experiment, 13 
for the second and 6 for the third, with 30 loaded 
freight cars in the train. The last experiment was 
made while the engine was working on a heavy grade 
and very nearly up to its maximum capacity. 

It will thus be seen that a great deal of heat is 
wasted by escaping up the chimney. 

Fourth, by external radiation from the boiler. This 
occurs chiefly from the fact that it is not sufficiently 
well protected or covered with non-conducting mate- 
rial. The practice, or rather the neglect, of not cover- 
ing the outside of the fire-box with lagging doubtless 
causes a very considerable loss of heat by radiation 
and convection from the hot boiler plates. 

Question 400. What is the ordinary form of Jlre-box 
employed for burning bituminous coal f 

Answer. It is that represented in plate II and figs. 
41 and 44, and is simply a rectangular box, and for 
tli at reason it is called a plain fire-box. Sometimes 
provision is made for admitting air into such fire- 
boxes through hollow or rather tubular stay-bolts, 
which are put into the sides and front. In most cases, 
too, the fire-box door has perforations for admitting air. 

Question 401. What other appliances are used for 
burning bituminous coal f 

Answer. The most common appliance which is added 
to the plain fire-box is what is called a fire-brick arch. 
This is shown in fig. 214. B G is the arch which, 
as its name implies, is formed of fire-brick and extends 
backward and upward from a point in the tube-sheet 
below the tubes. In order to be self-supporting it is 

34 



398 



Catechism of the Locomotive, 



built in the form of an arch, the two sides of the fire- 
box acting as abutments for its support. The engrav- 
ing represents with sufficient clearness the direction 
of the flames and smoke. These must take a more 
circuitous "run" as it is called, after leaving the fire, 
in order to reach the tubes. Time is thus given for 
the gases to combine and combustion to take place. 




Kg. 214. Scale % in.=l foot. 

The fire-brick becomes heated, and thus to some ex- 
tent prevents the gases from being cooled down below 
an igniting temperature by contact with the cold sur- 
face of the fire-box before combustion is complete. 
The fire-brick, however, soon burns out, and must be 
replaced, but owing to its cheapness and the ease 



Combustion, 



399 



with which it can be removed, this does not make a 
serious objection to its use. Air is nearly always ad- 
mitted above the fire when the brick arch is used, 
either by tubular stay-bolts, a } a, a, or perforations in 
the door, or both. 

In order to avoid the inconvenience and expense of 
replacing the fire-brick arch, what is known as the 




Fig. 215. Scale % in.=l foot. 
" Jauriet water-table " has been extensively used on 
some roads. This is the invention of Mr. C. F. Jau- 
riet and is represented in fig. 215, and consists of a 
flat " table," B G, formed of two boiler plates placed 
about 4^ in. apart, with the space between filled with 
water. The two plates are stayed with ordinary stay- 



400 Catechism of the Locomotive. 

bolts in the same way as the sides of the fire-box. The 
form of the water-table is similar to that of the fire-brick, 
excepting that it is not arched, this form not being 
necessary, as the plates are riveted to the sides of the 
fire-box. Air is admitted above the fire both by hol- 
low stay-bolts and holes in the door, as shown at A. 
Tubes, f, are put into the front and lower portion of 
the water-table to allow the ashes and cinders, which 
would otherwise be deposited above, to fall down on 
the grates. 

When air is admitted at the furnace door of an or- 
dinary fire-box, it is very apt to rush directly into the 
tubes without mingling with the gases. It was found 
by some of the firemen on English railroads that by 
placing a shovel over the top of the furnace door, the 
current of air which entered could thus be deflected 
downward, and in this way smoke could be almost en- 
tirely prevented. This led to the adoption of a hood 
or deflector, A, fig. 216, which is made of sheet iron and 
is placed over the fire-box door and is arranged with 
a lever, B, so that it can be raised in order to be out 
of the way when coal is thrown on the fire. It is sus- 
pended from a hook, G, from which it can easily be 
detached and taken out for repairs. This is frequently 
necessary, as the intense heat of the fire-box burns 
away the sheet iron of which it is made very rapidly. 
It can be made of old boiler plate, so that the expense 
of renewal is very slight. When this plan is used, 
a double sliding door, shown in fig. 217, is commonly 
used with it. These doors are opened by the levers/ 
d, and e g, which are all connected together. With 
these sliding doors the opening for the admission of 
air can easily be regulated, and the opening through 



Combustion. 



401 



which the lever, B, is attached to the deflector, A, can 
he arranged more conveniently than with a swinging 

Fig. 216. 




34* 



Fig. 217. 
Scale % in. = 1 foot. 



402 



Catechism of the Locomotive. 



door. This plan has been employed by the Rogers 
Locomotive Works. 

Another plan of fire-box, which was designed and 
patented by Mr. William Buchanan, Master Mechanic 
of the Hudson River Railroad, and used extensively 
on that line, is shown in fig. 218. This consists of a 




Fig. 218. Scale % in. = 1 foot. 

water-table, but it extends completely across the fire- 
box from the tube sheet to the back-plate, thus divid- 
ing the fire-box into two compartments, M and N. In 
order to afford communication from the lower one to 
the upper one a round hole, Z>, about 24 in. in diame- 
ter, is put in the water-table in the position shown. 
It will thus be seen that all th© currents of gas, smoke 



Combustion. 403 

and air must unite in passing through this opening, 
and are thus brought into close contact with each 
other, Alter they enter the upper chamber and before 
they enter the tubes, there is room and time for com- 
bustion. The position of the lower side of the table, 
it will be seen, is similar to that of the deflector shown 
in fig. 216, so that it acts in somewhat the same way, 
by directing the currents of air, which enter through 
the furnace door, downward on the fire. 

Question 402. How do these different plans operate ? 

Answer. They will all burn coal more perfectly, and 
therefore more economically, if they are carefully and 
skillfully managed, than is possible in ordinary plain 
fire-boxes ; but it is probable that more economy in the 
consumption of coal would result from the improve- 
ment of the practice and knowledge of firemen than 
can be expected from the use of any of the appliances 
described, if they are used without care, or knowledge 
of the principles of combustion. 

Question 403. In what respect does anthracite coal 
differ from bituminous? 

Answer. It differs chiefly in the fact that it contains 
a much larger proportion of carbon and less of hydro- 
gen, and in the fact that it consequently gives off very 
little or no coal gas. Its combustion is therefore more 
simple than that of bituminous coal, as there is very 
little else than solid carbon to burn. 

Question 404. In what kind of a fire-box is anthra- 
cite usually burned? 

Answer. It is usually burned in a very long grate, 
and as the heat is very intense, the grate-bars are 
usually made of iron tubes, through which a current of 
water circulates, so as to prevent them from melting. 



404 Catechism of the Locomotive. 

Question 405. Is it important to admit air above an 
anthracite fire to facilitate combustion "} 

Answer. As there are no gases to be burned, it is 
not so important as it is with bituminous coal, but if 
the layer of anthracite on the grates is very thick, it 
will be impossible to get enough air through the coal 
to convert all the carbon into carbonic dioxide, and the 
carbon and oxygen will therefore unite so as to form 
carbonic oxide. If air is admitted above the fire, as has 
already been explained, another equivalent of oxygen 
will unite with the carbonic oxide, and a second com- 
bustion will then take place above the fire, and the car- 
bonic oxide will thus be converted into carbonic diox- 
ide. If, under these circumstances, no air was admit- 
ted above the fire, the second combustion would not oc- 
cur, and all the heat produced thereby would be lost. 

Question 406. How can we determine the relative 
value of different kinds of fuel for use in locomotives? 

Answer. This can only be determined satisfactorily 
by actual experiment. The chemical composition, ex- 
cepting so far as it indicates the presence of deleteri- 
ous substances, such as sulphur, ashes, clinkers, etc., 
affords but little assistance in determining the value 
of fuel. Nearly the same quantities of elements in dif- 
ferent fuels may arrange themselves, before and during 
combustion, so as to produce very different series of 
compounds. It is true that the composition of coal 
gives us some indication of its heat-producing capacity, 
but the extent to which that capacity can be converted 
into actual steam in locomotive boilers, depends to a 
very great extent upon the conditions under which the 
fuel is burned. It should also be remembered that 
the rapidity with which steam can be generated is a 



Combustion, 405 

very important matter in locomotive practice. Wheth- 
er a heavy freight train can be taken up a given grade, 
or a fast express make time, often depends upon the 
amount of steam which can be generated by the fuel 
in each second of time that the boiler is worked to its 
maximum capacity. Therefore any appliance for im- 
proving combustion, which reduces the quantity of 
steam which can be generated by the boiler in a given 
time, is quite sure to fall into disuse or be abandoned. 
It is of course often necessary to adapt the appliances 
for burning fuel to the fuel itself; and when a poor 
quality of the latter must be used, more boiler ca- 
pacity must be given than is needed to do the same 
work with better fuel. 

The table in the appendix will no doubt be valuable 
as indicating the properties an(J relative value of several 
different kinds of fuel used in this country. The table is 
copied from a report made to the Navy Department of 
the United States by Professor Walter B. Johnson in 
1844, and the conclusions are deduced from a series of 
very elaborate experiments made for the Navy De- 
partment. This report furnishes the most full and re- 
liable data regarding the value of American fuel thus 
far (1874) published ; but it contains little or no in- 
formation concerning the fuels which are now used on 
railroads in our Western States. The first eight speci- 
mens of coal given in the table are anthracite j all the 
rest are bituminous coals. 



PART XX. 



THE RESISTANCE OF TRAINS. 



Question 407. What is meant by the resistance of 
trains or cars f 

Answer. It is the power required to move them on 
the track. Thus if a rope, fig. 219, was attached to a 
car at one end, and the other passed over a pulley, a, 
and a sufficiently heavy weight, W, was hung on the end 
of the rope, it would move the car. The weight W 
would then he equal to the resistance of the car. 

Question 408. How can the resistance of cars linden 
different circumstances be determined? 




© 



Fig. 219, 
Answer. It has been found that it takes a force of 
about 6 lbs. per ton (of 2,000 lbs.) to move a car slowly 
on a level and straight track after it is started. That is, 
if a car weighs 20 tons and a rope, fig. 219, is attached 
to it at one end and the other passed over a pulley, a, 
with a weight, W } suspended to it, it will require & 



The Resistance of Trains* 



m 



weight equal to 20 x 6 = 120 lbs, to keep the car 
moving slowly. If two cars of the above weight were 
coupled together, it would require twice 120 or 240 
lbs., and if three were attached to each other, three 
times 120, or 360 lbs., and so on. In other words, 

MULTIPLYING THE TOTAL WEIGHT OF THE CARS IN 
TONS (OF 2,000 LBS.) BY 6 WILL GIVE US THEIR RE- 
SISTANCE, OR THE FORCE REQUIRED TO KEEP THEM 
MOVING ON A LEVEL AND STRAIGHT TRACK AT A SLOW 

speed after they are started. The resistance is 
represented by the weight above, and the locomotive 
must exert a force equal to that weight to keep the 
train moving. As the speed increases the resistance 
increases, as is shown by the following table. It 
should be stated here, however, that our knowledge 
regarding this whole subject of the resistance of Amer- 
ican cars and trains is exceedingly inaccurate and im- 
perfect, and the data given in the books are nearly all 
based on experiments made in Europe, with cars of a 
different construction from those used here. There is 
reason for believing, however, that the resistance of 
American cars is less than that of European cars, and 
we have assumed it to be 6 lbs. per ton on a level at 
very slow speed, which is less than the resistance which 
is usually given, but the following figures should be 
regarded merely as an approximation to the actual 
facts, of which we are still in ignorance: 



Velocity of trains in 
miles per hour 


5 


10 


15 


20 


25 


30 


35 


40 


45 


50 


60 


70 


Resistance on straight 
line in lbs. per ton 
(of 2,000 lbs.)....... 


6.1 


6.6 


7.3 


S.3 


9.6 


11.2 


13.1 


15.3 


17.8 


20.6 


27 


34.6 



Now, if we want to get the resistance at 30 miles 
an hour of a train of ten cars weighing each 20 tons, 



408 Catechism of the Locomotive. 

the calculation would be 10 X 20 X 11£ = 2,250 lbs. 
This will give the resistance on a level and straight 
track. On an ascending grade the resistance is 
greater than that given above, because, besides pulling 
the car horizontally, it is necessary to raise it verti- 
cally a distance equal to the ascent of the grade. Thus 
if we have a grade with a rise of forty feet in a mile, the 
amount of energy required to simply raise the weight of 
a car would be equal to its weight in pounds multiplied 
by the vertical height of the asceut. Thus, supposing 
a car which weighs 40,000 lbs. to be run one mile on a 
grade of forty feet ascent in that distance, then the 
energy expended in simply raising the car will be equal 
to 40,000 X 40 = 1,600,000 foot-pounds. Now, if it 
was necessary to raise that weight by a direct vertical 
lift or pull, it would require a force equal to or a little 
greater than the load to do it. But in pulling a car or 
train up a grade, which is an inclined plane, the force, 
which is the locomotive, instead of being exerted 
through the vertical distance is exerted through the 
horizontal distance, which in this case is one mile, or 
5,280 feet. Therefore, if we divide the number of foot- 
pounds of energy required by the distance through 
which the power is exerted, it will give us the force ex- 
erted through one foot. That is, 

1,600,000 

= 151.5 lbs. 

5,280 

The resistance due to the ascent alone of a train on 
a grade or incline can therefore be calculated by mul- 
tiplying THE WEIGHT OF THE TRAIN IN POUNDS 
BY THE ASCENT IN ANY GIVEN DISTANCE IN FEET 
AND DIVIDING THE PRODUCT BY THE HORIZONTAL 



The Resistance of Trains. 409 

distance in feet. Thus in the above example 
the rate of the ascent is given in so many feet per 
mile ; we therefore multiply by 40 and divide by 5,280, 
which is the number of feet in a mile. If the rate of 
the gradient had been given, as it sometimes is, as 1 
in 132, we would simply have divided the weight of 
the train by the latter number. If we want to get the 
resistance per ton of train we substitute for its weight 
that of one ton in pounds ; thus : 

2,000*40 „ 1lfc 
— — — — = 15.1 lbs. 

5,280 

If, now, we have the resistance which is due to the 
ascent or gravity alone, we must add to this the resist- 
ance on a straight and level track, at the speed at 
which the train runs, in order to determine the total 
resistance on the grade. On a level road at a speed of 
5 miles per hour it would be 6.1 lbs. per ton, so that 
on a grade of forty feet to a mile at that speed the re- 
sistance would be 6.1 + 15.1 = 21.2 lbs., per ton, and 
at 10 miles it would be 6.6 + 15.1 = 21.7 lbs., and 
at 30 miles per hour on the grade the resistance would 
be 11.2 -f 15.1 = 26.3 lbs. per ton. To get the total 
resistance on a grade for any speed, we add the re- 
sistance FOR THAT SPEED ON A STRAIGHT AND 
LEVEL LINE TO THE RESISTANCE DUE TO THE ASCENT 

alone. The resistances for various rates of speed and 
grades has been calculated, and is given in the table 
in the appendix. 

The top horizontal row of figures of that table gives 

the rates of speed. The left-hand vertical row gives 

the rise of grade in feet per mile. The resistance for 

any given grade and speed is given where the vertical 

35 



410 Catechism of the Locomotive. 

row of figures under the rate of speed and the hori- 
zontal row opposite the rise of the grade intersect 
each other. Thus, for a grade of 30 feet per mile and 
a speed of 45 miles per hour, we follow the vertical 
column under the 45 downward, and the horizontal 
column opposite 30 to the right, and where the two 
intersect the resistance, 29.1 lbs. is given. 

Question 409. What effect do curves have on the re- 
sistance of trains f 

Answer. They increase the resistance, but in what 
proportion or to what degree is not known accurately. 
European authorities say that the resistance is in- 
creased, over what it would be in a straight and level 
line, about 1 per cent, for every degree of the curve 
occupied by a train. It is probable, however, that the 
resistance of American cars, which nearly all have 
double trucks, is not so great on curves as that of 
European cars, which nearly all have long and rigid 
wheel-bases, and whose wheels therefore can not adjust 
themselves so easily to the curvature of the. track as 
they can when the American system of double trucks 
is used. 

Question 410. What is meant by a degree of a curve ? 

Answer. In order to measure circles, they are all 
supposed to be divided into 360 equal parts, which are 
called degrees. One degree of a curve is therefore 
^ of a complete circle; but if the curve has a 
long radius, one degree of such a curved track will 
be longer than one degree of a curve with a short 
radius, but each will have the same amount of 
" bend " or curvature. It is this latter which increases 
the resistance of trains, and the greater the number of 
degrees of a curve occupied by a train of cars, the 



The Resistance of Trains. 411 

greater will be the " bend " of the track, and therefore 
the greater the resistance. 

Question 411. What other causes affect the resistance 
of trains ? 

Answer. The condition of the track and the force 
and direction of the wind. On a rough track the re- 
sistance is very much greater than on a smooth one, 
and a strong head-wind makes it much more difficult 
to pull a train than it is in calm weather. 



PART XXI. 

PKOPOKTIONS OF LOCOMOTIVES. 

Question 412. In proportioning a locomotive to any 
given kind of work, what are the first facts which should 
be known f 

Answer. We should first know the weight of the 
train which the locomotive nmst draw; second, the 
speed at which it must run; and third, the steepest 
grades and the shortest curves of the road on which 
it must work. From these data the resistance of the 
train which the locomotive must overcome can be at 
least approximately determined. 

Question 413. When the greatest resistance of the 
train is known, what is the next thing to be determined? 

Answer. As was stated in answer to Question 66, if 
the wheels revolve and their adhesion is greater than 
the resistance opposed to the movement of the locomo- 
tive, the latter will overcome the resistance ; but if the 
latter is greater than the friction, the wheels will slip. 
It therefore follows that the adhesion must be some- 
what greater than the resistance. As the adhesion is 
equal to about one-fifth* of the adhesive weight or 
pressure of the driving-wheels on the rails, obviously 
this weight should be five times the resistance. Thus, 
if we have a train weighing 400 tons which we want 
to take up a grade of 40 feet per mile at a speed of 20 

•See answer to Question 809. 



Proportions of Locomotives. 413 

miles per hour, its resistance, calculated from the table 
given in the previous part, would be 9,360 lbs. There- 
fore, 9,360 X 5 = 46,800 lbs. == the required adhesive 
weight. 

Question 414. What considerations determine the 
manner of distributing this weight on the wheels f 

Answer. It is found by experience that if too much 
weight is placed upon one wheel, the material of which 
the rails are made is partly crushed and injured, and 
they then wear out much more rapidly than they 
would if the weight was distributed on more wheels, 
and thus a smaller amount of weight rested on each 
point of contact with the rails. The amount of weight 
which can be carried on a single wheel depends upon 
the material of which the rails are made, and to some 
extent on their form and size, or as the latter is usu- 
ally expressed, on their weight per jard. 

Question 415. When the adhesive weight and the num- 
ber of driving-wheels are known, how is the size of the lat- 
ter and of the cylinders determined ? 

Answer. The size of the wheels will to a certain ex- 
tent depend upon the speed, because the larger the 
wheels, the further will the locomotive move in one 
revolution; but no exact rule can be given for their 
size. At present there is still a great diversity of 
opinion among engineers regarding the best sizes of 
wheels and cylinders for any given service. Probably 
the safest plan will be to consult the best practice, and 
in the absence of any better reasons be guided for the 
present by that. In this country the most common 
size of locomotives used is that which we have selected 
for our illustrations, that is, what are called five-feet 
wheels, and cylinders of 16 inches diameter and 24 
85* 



414 Catechism of the Locomotive. 

inches stroke. More engines of these dimensions are 
used than of any other. For freight service the wheels 
are sometimes made of smaller and for passenger trains 
of larger diameter; but locomotives with driving- 
wheels and cylinders of the dimensions given are used 
for both passenger and freight service. It should be 
stated here that what are called five-feet wheels are 
usually about 1-J in. larger in diameter than five feet. 
This arose from the fact that the tires which are now 
used are made thicker than they were on the first en- 
gines, and the practice thus established has been con- 
tinued. We will therefore take the diameter of what 
is called a five-feet wheel at what it really is, 61J in. 
Such locomotives also have about 40,000 lbs. of adhe- 
sive weight. Now, the circumference of such wheels 
is 193.2 in., and therefore in one revolution of the 
wheels, if they do not slip, the locomotive will move 
that distance on the rails. At the same time each 
piston will sweep through the cylinder twice, and 
therefore in one revolution 4 times one cylinder full of 
steam is used. Now a cylinder of 16 in. diameter and 
24 in. stroke contains or will hold 4,825J cubic inches, 
so that in one revolution of the wheels 4,825^ X 4 = 
19,302 cubic inches of steam are used. As has been 
stated, in one revolution of the wheels, if they do not 
slip, the locomotive will move 193.2 in. If, now, we 
divide 19,302 by 193.2 it will give us the amount of 
steam used to move the locomotive and train one inch. 
Now, 19,302 + 193.2=99.9, which, for the sake of even 
figures we will call 100. We thus see that a locomo- 
tive with 40,000 pounds or 20 tons (of 2,000 lbs.) of 
adhesive weight requires 100 -uibic inches of cylinder 



Proportions of Locomotives. 415 

capacity* to move it one inch. Now, if a locomotive 
had only half as much weight on the driving-wheels, 
it could pull only half as much load, and would there- 
fore use only half as much steam, and consequently 
need only half the cylinder capacity of the other loco- 
motive. If there was three-quarters or a third as 
much adhesive weight, the cylinder capacity should also 
he three-quarters or a third. We thus see that the 
cylinder capacity should be proportioned to the total 
adhesive weight. Now as 100 cubic inches of cylinder 
capacity are needed to move an engine with 20 tons 
adhesive weight one inch, if we divide 100 by 20 we 
will get the cylinder capacity needed for each ton. 
That is, 100 ~- 20 = 5 cubic in. cylinder capacity 

PER TON (of 2,000 lbs.) OF ADHESIVE WEIGHT IS 
NEEDED TO MOVE ANY LOCOMOTIVE ONE INCH. This 

quantity we have named the modulus of propulsion. 

Supposing now that it is required to calculate the 
cylinder capacity for a locomotive with 15 tons adhe- 
sive weight, and wheels 4^ feet or 54 in. in diameter. 
We will first multiply 15 by the modulus of propul- 
sion, 15x5=75 = the number of cubic inches of cyl- 
inder capacity required to move such a locomotive one 
inch. Multiplying the length of the circumference of 
the wheels, which in this case is 169.6 in. by 75, will 
give us the total cylinder capacity for one revolution. 
That is 169.6x75=12,720 cubic inches of cylinder 
capacity, or the space which should be swept through 
by the two pistons. Dividing this by 4 will give us 
the cubical contents in inches of one of the cylinders. 



*The cylinder capacity is the space swept through by the two pistons. 
In the above illustrations what is meant is, that the average space in the 
cylinder swept through by the piston is 100 cubic inches for each inch 
that the locomotive advances. 



416 Catechism of the Locomotive. 

Thus, 12,720 H- 4 = 3,180 cubic inches = the capacity 
of one cylinder. Now as the capacity of a cylinder is 
calculated by multiplying the area of the piston by 
the length of the stroke, if we have the one we can 
easily determine the other. Thus, supposing it was 
intended to make the stroke of the pistons 22 in., divid- 
ing 3,180 by 22 will give us the area of the piston. 
Thus, 3,180 +-22= 144.5 square inches. Now by the 
well-known rule in mensuration, if we divide the 

AREA OF A CIRCLE BY 0.7854, THE SQUARE ROOT OF 
THE QUOTIENT WILL BE THE DIAMETER OF THE CIR- 
CLE. Thus, 144.5-^-0.7854 = 183.9. The square root 
of 183.9 is 13J- nearly, which should be the diameter 
of the cylinder. Instead of calculating the diameter 
of the circle, a more convenient way is to refer the 
area to a table of areas, and from it find the diameter. 
Of course if we have the diameter of the piston and 
want to get the stroke, we divide the cubical con- 
tents OF THE CYLINDER BY THE AREA OF THE PIS- 
TON. Thus, in the present illustration, if it was in- 
tended to have the piston 13 J in. diameter, we would 
have divided 3,180 by the area of a piston 13J in. 
diameter, which is 143.1, so that we would have 3,180 
—- 143.1 =z 22 nearly, == inches of stroke of piston. 
From the above considerations we can deduce the 

following RULE FOR CALCULATING THE CAPACITY 
OF THE CYLINDERS WHEN THE ADHESIVE WEIGHT IS 
KNOWN : 

Multiply the total weight on the driving- 
wheels IN TONS (of 2,000 lbs.) BY 5, AND THEN BY 
THE CIRCUMFERENCE OF THE WHEELS IN INCHES, 
AND DIVIDE BY 4. THE QUOTIENT WILL BE THE 
CUBICAL CONTENTS IN INCHES OF EACH CYLINDER. 



Proportions of Locomotives, 417 

From this, if either the diameter or stroke is given the 
other can easily be found, as has been explained. 

It should be remarked here that it is unimportant, 
so far as the power of the locomotive is concerned, 
whether the cylinders have a large diameter and a 
short stroke or a small diameter and a long stroke, 
provided the cubical contents are the same. Thus 
cylinders 17J in. in diameter and with 20 in. stroke 
would have almost exactly the same capacity and the 
same power would be exerted with them as with cyl- 
inders 16x24 in.; the only difference would be that 
with the cylinder of the largest diameter the pressure 
on the piston and consequently on the crank-pin jour- 
nal and the strain on the parts would be greater than 
with the smaller cylinder. The difference in pressure 
would, however, be exactly compensated by the loss or 
gain in the leverage exerted through the driving- 
wheels on the rails. 

Question 416. What circumstances should determine 
the size of locomotive boilers ? 

Answer. They should be proportioned to the amount 
of adhesive weight, and to the speed at which the loco- 
motive is intended to work. Thus, a locomotive with 
a great deal of weight on the driving-wheels could 
pull a heavier load and would, by the above rule for 
proportioning the cylinders, have a greater cylinder 
capacity than one with little adhesive weight, and 
would therefore consume more steam, and therefore 
should have a larger boiler. It is also obvious that if 
a locomotive like that shown in plates I and II should 
have a boiler just large enough to furnish steam when 
running at the rate of 20 miles an hour, it would be 
too small if the locomotive ran 40 miles an hour, the 



418 Catechism of the Locomotive. 

train resistance being the same in both cases. Driving- 
wheels 5 feet in diameter would at 20 miles per hour 
make 112 revolutions per minute, and would therefore 
consume 448 cylinders full of steam. At 40 miles per 
hour double the number of revolutions would be made, 
and consequently twice the quantity of steam would 
be used, and therefore the boiler should have twice the 
steam-producing capacity. If, therefore, we know the 
size of a boiler required for a given amount of adhe- 
sive weight and a given speed, we can easily calculate 
the boiler capacity for any other weight and speed. 

Question 417. How can we determine the boiler ca- 
pacity needed for an engine with a given amount of adhe- 
sive weight and for a given speed ? 

Answer. This must be determined empirically, that 
is from experience. 

Question 418. On what does the steam-generating 
capacity of a boiler depend*? 

Answer. First, upon the size of its grate and fire- 
box, because more fuel can be burned in a large fire- 
place than in a small one ; second, on the amount of 
heating surface to which the products of combustion 
are exposed, and third, on the draft produced by the 
blast or exhaust steam. Of course the amount of 
steam generated is also dependent upon a great va- 
riety of other circumstances, such as the nature of the 
combustion, the firing, the arrangement of the fire- 
box, grates, etc., and the condition of the heating sur- 
faces ; but these have nothing to do with the propor- 
tions or size of the boiler. 

Question 419. What are the proportions of boilers 
used in locomotives like that which has been illustrated in 
these articles and represented in Plates I and II ? 






Proportions of Locomotives. 419 

Answer. The area of the grate is about 2,100 square 
inches and the total heating surface about 800 square 
feet, and the water capacity about 5,000 lbs., and the 
total weight of the boiler, including all the boiler at- 
tachments and appliances for promoting combustion, 
about 30,000 lbs. 

Question 420. At what speed are such engines usu- 
ally run ? 

Answer. The speed varies so much under different 
circumstances, that it is impossible to give even ap- 
proximately the average speed of such engines. 

Question 421. How then can we determine the proper 
proportions of a boiler for a locomotive intended for any 
given service? 

Answer. As stated before, this can only be done em- 
pirically. The safest method is to select a locomotive 
which is doing the best service, and learn the average 
speed at which it runs, the size of its grate and the 
amount of its heating surface, and its adhesive weight. 

NOW MULTIPLY THE ABOVE SPEED IN MILES PER 
HOUR BY THE ADHESIVE WEIGHT OF THE LOCOMO- 
TIVE IN TONS (of 2,000 lbs.) AND DIVIDE THE PRODUCT 

into the area of the grate in square inches. 
Then multiply the adhesive weight of the 
locomotive for which the boiler is to be 
provided by its speed, in miles per hour, and 
by the quotient obtained above : the product 
will be the area of the grate in square inches 
for the new engine. To illustrate this, suppose 
an engine of the dimensions given to run at an aver- 
age speed of 20 miles per hour. Now, multiplying 
that speed by the number of tons of adhesive weight 
and dividing the product into the area of the grate, we 



:i 



420 Catechism of the Locomotive. 

have 20x20=400 and 2100-^-400=5.25. We now 
want to determine the size of a grate for the boiler of 
a locomotive with 30 tons adhesive weight and to run at 
a speed of 15 miles per hour. We therefore multiply 
15 by 30 and the product by the above quotient, or 
15x30x5.25=2,362.5 = square inches of grate sur- 
face for the boiler. The required heating surface can 
be obtained in a similar way, by substituting it instead 
of the grate surface in the calculations. 

Question 422. How is the size of locomotive boilers 
usually limited? 

Answer. By the weight of the locomotive and to 
some extent by the distance between the rails. It will 
be found often that it is impossible to make the boiler of 
the size indicated by a calculation similar to the above 
without at the same time making the weight of the 
locomotive and the adhesive weight greater than was 
assumed. The result of such a calculation indicates, 
therefore, that too large a proportion of the weight of 
the locomotive is on the driving-wheels for the speed 
at which it is intended to work, and that either they 
should bear less weight or the speed be reduced. 

Question 423. In what respects is the operation of 
locomotive boilers different from that of nearly all other 
steam boilers ? 

Answer. The amount of steam generated in propor- 
tion to the amount of heating surface is much greater 
in locomotive boilers than in any other kind. To 
produce combustion which will be sufficiently active 
to generate the requisite quantity of steam, the fire 
must be stimulated by the blast created by the exhaust 
steam to a degree unknown in other kinds of boilers. 
So rapid is the movement of the products of combus- 



Proportions of Locomotives. 421 

tion that a smaller proportion of the heat is imparted 
to the water contained in the boiler, and consequently 
a less amount of water is evaporated in proportion to 
any given amount of fuel than in boilers in which 
combustion is less violent. The combustion is also 
less perfect, because the strong draft does not allow 
time for a perfect combination of the gases which pro- 
duce combustion. 

The supply of steam which a locomotive boiler must 
furnish is also much more irregular than the demands 
made upon any other kind of boiler. At one time the 
fire must be urged to the greatest possible intensity 
in order to furnish steam enough to pull a train up a 
steep grade. When the top is reached the demand 
ceases, and the boiler can be cooled. The load which 
a locomotive can pull over a given line of road is 
usually limited by the utmost capacity of the boiler to 
supply steam at these critical periods. 

Question 424. What relation is there between this ir- 
regular action and the size of the boiler? 

Answer. The smaller the boiler, or rather the larger 
the amount of steam which must be generated in a 
given time in proportion to the heating surface, the 
more must the fire be urged ; and therefore the smaller 
the boiler in proportion to the work it must do, the less 
will be its economy. In order to produce a rapid com- 
bustion in a small boiler, it is necessary to contract 
the exhaust nozzles in order to create a draft strong 
enough. In doing this the back pressure on the pis- 
tons is very much increased, and when the blast be- 
comes very violent a great deal of solid coal is carried 
through the tubes and escapes at the smoke-stack un- 
consumed. At the same time large quantities of un- 
36 



422 Catechism of the Locomotive. 

consumed gases escape, because there is not time for 
combustion to take place in the fire-box. The fact 
that with a violent draft the flame and smoke are in 
contact with the heating surface for a sensibly shorter 
period of time also has its influence ; as less heat will 
be imparted to the water if the products of combus- 
tion are only T J-^ of a second instead of t §q in passing 
through the tubes. 

There is another consideration which should be 
taken into account in this connection, which is, that if 
a boiler is so small that it is worked nearly up to its 
maximum capacity at all times, it will be impossible 
to accumulate any reserve power in it in the form of 
water heated to a high temperature to be used as occa- 
sion may require. With a boiler having a great 
amount of heating surface and capacity for carrying a 
large quantity of water, the latter can be heated at 
times when the engine is not working hard, and the 
heat thus stored up in the water can then be used when 
it is most needed. Thus we will suppose that to pull a 
train of cars on a level 250 lbs. of steam are consumed 
per mile. On a grade of 30 feet per mile the resist- 
ance will be three times what it is on a level, and 
therefore three times the quantity of steam will be 
consumed, so that the boiler must then evaporate 750 
lbs. of water per mile. Now to convert 250 lbs. of 
water heated up to a temperature due to 130 lbs. of 
effective pressure, or 355.6 degrees, into steam of that 
pressure will require 216,575 units of heat. If at the 
same time that this steam is being consumed, we pump 
into the boiler 250 lbs. of water of a temperature of 
60 degrees, 73,900 more units of heat will be needed 
to raise the water to the temperature due to 130 lbs, 



Proportions of Locomotives, 423 

effective pressure, so that on the level part of the road 
it would be necessary to transmit to the water in the 
boiler 216,575 + 73,900=290,475 units of heat in a 
mile. If there is no room in the boiler for storing a 
surplus quantity of hot water, it will be necessary on 
a grade as fast as the steam is consumed to feed an 
equivalent amount of cold water to take the place of 
that which was converted into steam, so that on a 30 
feet grade it would be necessary to convert at the rate 
of 750 lbs. of hot water into steam in a mile, which 
would require 649,725 units of heats, and at the same 
time heat an equal amount of cold water to a temper- 
ature due to the pressure of the steam, which would 
require 221,700 more units. So that it will be neces- 
sary to transmit at the rate of 871,425 units of heat 
to the water per mile. Now if the boiler was so large 
that more water could be pumped into it and heated 
than was used on the level portion of the road, and 
could there be stored up for future use, the pumps 
might be either partly or entirely shut off when the 
engine was working the hardest on the grade. In this 
way, instead of being obliged to convert hot water 
into steam, and at the same time heat an equal amount 
of cold feed-water, there would be a surplus of hot 
water stored up already heated. It would therefore 
only be necessary to convert this hot water into steam, 
which will require a transmission of heat to the water 
at the rate of 649,725 units of heat instead of 871,425. 
It must be remembered that on nearly all roads there 
are certain difficult places which practically limit the 
capacity of the locomotives on that line. If therefore 
the capacity of the engines can be increased at those 
points, their capacity over the whole line is increased- 



! 



424 Catechism of the Locomotive. 

It will be seen by the above illustration that by having 
a large boiler it is necessary for it to do very much 
less work at the critical period, when, as every loco- 
motive runner knows, it is often of the utmost impor- 
tance to make use of every possible available means in 
order to pull the trains. It is true that on a very 
long grade the supply of surplus hot water would soon 
be exhausted, but even in such cases there is usually 
one place, owing to a curve or other cause, which is 
more difficult to surmount than any other, in which 
case it will be necessary to use more steam for a short 
time than the locomotive can generate if the boiler is 
fed continuously. For such cases a surplus of water 
can be used. But even if the resistance is equal over 
the whole length of the incline, still the large boiler 
will have the advantage, because it can at all times 
generate more steam than a smaller one. It may 
therefore, we think, safely be assumed that locomotive 
boilers should always be made as large as the weight 
of the locomotive will permit. 

Question 425. What effect does the size of the driving- 
wheels have upon the combustion and evaporation of lo- 
comotive boilers ? 

Answer. As small wheels make more revolutions in 
running a given distance than large ones, there will 
be more strokes of the piston with the former than 
with the latter, if the locomotive in both cases runs at 
the same speed. As smaller cylinders are usually em- 
ployed with small wheels, the blast up the chimney is 
then composed of a larger number of discharges of 
steam, but each one of less quantity, than when larger 
wheels and cylinders are used. In the one case the 
" puffs " of steam are many and small, and in the lat- 



Proportions of Locomotive*. 425 

ter few and large. If the cylinders are proportioned 
by the rule which has been given for that purpose, the 
amount of steam discharged in running any given dis- 
tance will be the same with engines having large 
and those with small wheels, the only difference being 
that it will be subdivided into a greater number of 
discharges in the one case than in the other. Now, it is 
found that the draft of engines is much more effective 
on the fire when the blast is thus subdivided, that is 
when small wheels and cylinders are used, than it is 
with large ones, and therefore more steam is generated 
with the former than with the latter. 

Question 426. What relation is there between the size 
of the wheels and that of the boiler % 

Answer. As has been explained, the size of the 
boiler is limited by the weight of the locomotive. The 
boiler and its attachments of an American locomotive, 
when the former is filled with water, weigh about half 
as much as the locomotive; therefore unless we in- 
crease the weight of the latter or decrease the weight 
of the machinery, we can not increase the size of the 
boiler. Now, large wheels are heavier than small 
ones ; they require larger cylinders, stronger connec- 
tions, heavier frames, and in fact nearly all the parts 
of the machinery used with large wheels must be 
heavier than are required when small wheels are used. 
Therefore, by decreasing the size of the wheels all the 
other parts of the engine proper can be made lighter 
than is possible if large wheels are used, and thus the 
size and weight of the boiler can be increased with- 
out increasing the whole weight of the locomotive. 
There is of course a practical limit below which the size 
of the wheels can not be reduced, because the speed of 
36* 



426 Catechism of the Locomotive. 

the piston would become so great as to be injurious to 
the machinery. By reducing the stroke, however, with 
the diameter of the wheels, the evil referred to may be 
obviated to a great extent. A cylinder with a large 
diameter and comparatively small stroke has also the 
advantage that there is less surface exposed to radia- 
tion of heat than there is in a cylinder in which these 
proportions are reversed. 



PART XXII. 
DIFFERENT KINDS OF LOCOMOTIVES. 

Question 427. Into what classes may locomotives he 
divided conveniently ? 

Answer. 1. Locomotives for "switching," "shunt- 
ing" or " drilling" service, that is, for transferring 
cars from one place to another at stations ; 2, for 
freight traffic ; 3, for ordinary passenger traffic, and 4, 
for suburban or metropolitan railroads, where a great 
many light trains are run. 

Question 428, What kinds of locomotives are used in 
this country for switching cars at stations ? 




Fig. 220. 

Answer. Four-wheeled locomotives similar to that 
shown in Plate IV. In some cases they are made 
with six driving-wheels. Engines like that shown in 
Plate IV have separate tenders, but they are some- 
times made so as to carry the water-tank and fuel on 
the locomotive itself, as shown in fig. 220, and are 



428 Catechism of the Locomotive, 

then called tank locomotives. Fig. 220 represents a 
switching engine built by the Taunton Locomotive 
Manufacturing Company. 

Question 429. Why are four-wheeled locomotives used 
for switching ? 

Answer. Because in such service it is constantly 
necessary to start trains, many of which are very 
heavy, and therefore a great deal of adhesion is needed. 
For this reason the whole weight of the locomotive 
and in the case of tank locomotives that of the water 
and fuel is placed on the driving-wheels. It is also 
necessary for such locomotives to ran over curves of 
very short radius and into switches whose angle with 
the main track is very great, and therefore in order 
that they may do this and remain on the track, their 
wheel-bases must be very short, and consequently the 
wheels are all placed near together between the smoke- 
box and fire-box. 

Question 430. Why are such locomotives not suited 
for general traffic ? 

Answer. Owing to the shortness of their wheel-bases 
they become very unsteady at high speeds, and ac- 
quire a pitching motion, similar to that of a horse-car 
when running rapidly over a rough track. This un- 
steadiness not only becomes very uncomfortable to the 
men who run the locomotive, but there is danger of 
the engine running off the track. As nearly all 
switching is done at very slow speeds, it is not so ob- 
jectionable for that service as it would be on the "open 
road "* at high speeds. 



* The term " open road" is a literal translation from the German, for 
which there is no corresponding English term, and means the road be- 
tween stations where trains run fast. 



Different Kinds of Locomotives. 429 

Question 431. What kinds of locomotives are used 
for freight service ? 

Answer. The greater part of the freight service of 
this country is performed by locomotives like that se- 
lected for the illustrations of these articles, and repre- 
sented in Plates I, II and III. Such locomotives have 
been called " American " locomotives because they first 
originated in this country and are now more generally 
used here than anywhere else. Side elevations of lo- 
comotives of this kind, built by the Baldwin Locomo- 
tive Works, the Grant Locomotive Works, the Dan- 
forth Locomotive and Machine Company, the Mason 
Machine Works and the Hinkley Locomotive Works 
are represented in Plates V, VI, VII, VIII and IX. 
Such locomotives have been described in the preceding 
pages. 

Question 432. What are the dimensions of such en- 
gines ? 

Answer. The principal dimensions of the engines 
illustrated are given in the table in the appendix, but 
locomotives of this plan are built of much smaller and 
also of larger sizes than those represented by the en- 
gravings. In some cases such locomotives do not 
weigh more than 35 or 36,000 lbs., with cylinders 
from 8 to 12 inches in diameter. In other cases they, 
weigh as much as 66,000 lbs., with cylinders 17 or 18 
inches in diameter. The wheels vary from 4 to 6 feet 
in diameter, but the most common sizes are 4J and 5 
feet 

Question 433. When it is desirable to pull heavier 
loads than is possible with the adhesive weight that can be 
placed on four driving-wheels, what is done ? 

Answer. One or more pairs of driving-wheels are 



430 Catechism of the Locomotive. 

added, as in the ten-wheeled locomotive represented 
in Plate X, the "Mogul" engine, Plate XI, and the 
" Consolidation " engine, Plate XII. The ten-wheeled 
locomotive, it will be seen, is similar in construction to 
an ordinary American locomotive, excepting that it 
has another pair of driving-wheels in front of the 
main driving-wheels. It will be seen, however, that 
it is necessary to keep these close to the latter, be- 
cause if they are brought further forward they will be 
too near the back truck-wheels. For this reason a 
truck consisting of a single pair of wheels, A, A, is 
placed in front of the cylinders, as represented in 
Plates XI and XII, is now much used. The front 
driving-wheels are then placed further forward, and 
thus bear a larger proportion of weight than they do 
in locomotives like that shown in Plate X. 

Question 434. How are trucks with a single pair of 
wheels constructed ? 

Answer. The truck frame is extended some distance 
behind the truck-axle, as shown in fig. 221, and the 
centre-pin, a, about which it vibrates, is placed at the 
back end. The weight of the locomotive, or that por- 
tion to be carried on the truck, is then made to rest 
over the centre of the axle, but in such a way that it 
can move laterally or crosswise over the track. Such 
trucks were first made so that the weight of the en- 
gine rested on slides on the truck frame, but recently 
they are nearly always suspended on links, so that they 
can swing like a pendulum, as shown in figs. 190 and 
191. The weight of the engine then rests on the cen- 
tre-plate, H H, which forms part of the plate, B B. 
This is suspended by links, L L, represented by dotted 
lines, which are attached by bolts to the cross-pieces, 



Different Kinds of Locomotives. 431 

m m, which are fastened to the truck frame. In this 
way the truck-wheels can move sidewaj^s independent 
of the engine itself. As the wheels and axles, A A, 
must move about the centre-pin, a, fig. 221, the axk 
assumes a radial position to the curves of the track. 
It does this, too, quite independent of the driving- 
wheels, as is shown in fig. 221, which represents a 




432 Catechism of the Locomotive. 

plan of the wheels on a curve. It will he seen that 
the truck is not at all influenced hy the position of the 
driving-wheels. This arrangement therefore gives 
sjreat flexibility to the wheel-base, and enables the 
wheels to adjust themselves to any lateral curvature 
or alignment of the track. 

Question 435. For what purpose are locomotives like 
that shown in Plates XI and XII used ? 

Answer. " Mogul " locomotives are often used for ordi- 
nary freight service where heavy trains must be hauled, 
and also on steep grades. Consolidation locomotives, 
represented in Plate XII, which have eight driving- 
wheels, are employed almost exclusively for traffic over 
heavy mountain grades. 

Question 436. What other hinds of locomotives are 
used for freight traffic ? 

Answer. Various kinds of tank locomotives, that is, 
locomotives which have no separate tenders, but carry 
the water-tanks and fuel on the frame and wheels of 
the locomotive itself, have been devised and are to 
some extent used. Plate XIII represents a locomo- 
tive of this kind on which the tanks are placed on 
each«side of the boiler, and the fuel on a Bissell truck 
at the back end. A similar truck is placed at the 
front end, so that a locomotive of this kind can run 
equally well either way. The lateral movement of 
the two trucks also gives great flexibility to the wheel- 
base, so that such an engine will adjust itself easily to 
the curvature of the track. If, however, the two pairs 
of truck- wheek should both stand on an elevated part of 
the track, and the driving-wheels on a depression, the 
latter would evidently not carry as much and the 
truck-wheels would carry more of the weight of the 



Different Kinds of Locomotives. 433 

engine than they did on a level part of the track. If 
the reverse condition of things should occur, that is, if 
the driving-wheels should be on an elevation and one 
or both pairs of the truck-wheels on a depression, 
then the latter would bear less weight than they did 
and the driving-wheels more. For this reason, in 
order to distribute the weight evenly on all the wheels, 
it is necessary to equalize the weight on the truck 
and driving-wheels, by connecting them with equaliz- 
ing levers, similar to those which were described in 
answer to Question 301. These levers distribute any 
undue weight which may come on one wheel to that 
next to it. This is important, because if the driving- 
wheels bore less weight at some times than at others, 
their adhesion and their capacity to draw loads would 
be reduced in like proportion. 

It is evident, however, that if the water-tank or 
fuel is carried on the driving-wheels, there will be a 
greater weight on them when the tank is full than 
when it is empty, and that therefore there will 
either be so much weight on the wheels at one time 
as to be injurious to the rails, or else there will be too 
little for adhesion at another. Of course cases are 
conceivable, and doubtless exist in practice, where 
more adhesion is required to start a train and haul it 
during the first part of the " run " than will be needed 
during the latter part. In such cases doubtless the 
variable character of the weight might be an advan- 
tage instead of the reverse, but for ordinary practice 
a variable load on the driving-wheels would have the 
disadvantages which have been described. For this 
reason tank locomotives have been built like that rep- 
resented in Plate XIV. In this it will be seen that 
37 






434 Catechism of the Locomotive. 

the weight of the water-tank rests on a four-wheeled 
truck at the back end. A Bissell or two-wheeled 
truck is, however, placed in front in the same position 
as in the engine represented in Plate XIII, and carries 
a portion of the weight of the boiler and machinery. 

In order to get all the advantages which a four- 
wheeled switching engine possesses in having its 
whole weight on the driving-wheels, and at the same 
time avoid the disadvantages which result from a short 
wheel-base, and also from a varying amount of weight 
on the driving-wheels, a locomotive like that repre- 
sented in Plate XV was designed by the writer with 
the whole weight of the boiler and machinery resting 
on the driving-wheels, and the water and fuel on a 
truck. By this means not only the objections to carry- 
ing the weight of the water on the driving-wheels is 
overcome, but at the same time the disadvantages 
arising from the short wheel-base of the switching lo- 
comotive, Plate IV, are also obviated. That is, all the 
permanent weight of the boiler and machinery of such 
a locomotive rests on the driving- wheels, and is there- 
fore all adhesive weight, as it is in the switching en- 
gine, and at the same time by extending the frame 
be3 r ond the fire-box and placing the water-tank and 
fuel on this extension of the frame and supporting 
their weight on a truck, the engine has a wheel-base 
which is as long and as flexible as that of ordinary 
American engines, represented in Plates V, VI, VII, 
VIII and IX, and as the latter have only about two- 
thirds of their weight on the driving-wheels, locomo- 
tives like that represented in Plate XV, of the same 
weight as the others, have fifty per cent, more adhe- 
sion, or they may be one-third lighter and have the 



Different Kinds of Locomotives. 435 

same adhesion. As was explained in answer to Ques- 
tion 260, if an ordinary American locomotive runs 
backwards, that is, with the driving-wheels in front, 
the friction of their flanges against the rails on curves 
of short radius will be very excessive. To avoid this 
with locomotives of the design last described, they are 
run with the truck first, which, being at the opposite 
end of the boiler from the position which it usually oc- 
cupies, reverses the position of the boiler and other 
parts relative to the motion of the engine. That is, 
the fire-box is then in front and the smoke-stack be- 
hind. Engines of this kind have been built and are 
now working and doing excellent service ; but the 
prejudice which exists against running locomotives in 
the reverse direction to what has been customary 
seems to be the chief obstacle in the way of their use. 
Another plan which possesses all the advantages of 
the locomotive described above and is free from the 
last objection is represented in Plate XVI. This 
plan was first adopted by Mr. Robert Fairlie in Eng- 
land, but has been introduced into this country and 
very much improved by Mr. William Mason, of Taun- 
ton, Mass. In these locomotives, the driving-wheels 
and cylinders are attached to a truck frame which 
turns around a centre-pin like any ordinary truck. 
The steam and exhaust pipes are connected to the 
boiler and cylinder with pipes which have flexible 
joints. By this means the truck can move independ- 
ently of the boiler, and thus the driving-wheels can 
adjust themselves to the curvature of the track, just as 
the wheels of any other truck do, and therefore the 
driving-wheels can be run ahead just as well as the 
truck-wheels which carry the tank. This plan pos- 



436 Catechism of the Locomotive. 

sesses the additional advantage that the fire-box can 
be made as wide and as long as may be desired with- 
out interfering with the driving-wheels. The flexible 
pipes are, however, usually considered an objection ; 
but with the improvements which have been made in 
their design and construction, the difficulties which 
were at first encountered have probably been over- 
come. At any rate if there is no other objection to 
the use of such locomotives, ingenuity and care should 
in time overcome that one. Plate XVII represents a 
locomotive of this plan, with six driving-wheels and a 
six-wheeled carrying truck under the tank. This lat- 
ter plan of locomotive is intended for heavy freight 
traffic. 

Question 437. What hind of locomotives is used for 
passenger trains? 

Answer. Eight-wheeled American locomotives are 
used almost exclusively for passenger service. Usu- 
ally the driving-wheels of such locomotives are larger 
in diameter than are used for freight traffic. Their 
size varies from 5 feet to 5 ft. 9 in. in diameter. The 
locomotive by the Mason Machine Works represented 
in Plate VIII has 5J feet driving-wheels. For very 
heavy express trains locomotives with 17x24 inch 
cylinders and weighing 34 tons are now used on many 
through lines. 

Question 438. What is meant by suburban and met- 
ropolitan railroads, what is the nature of their traffic, 
and what kinds of locomotives are needed for it ? 

Answer. The traffic of suburban railroads consists 
chiefly of the transportation of passengers who do 
business in the city to the latter in the morning and 
to their homes in the evening. As the largest num- 



Different Kinds of Locomotives. 437 

ber of passengers must be carried during a few hours 
in the morning and evening, it is necessary to run 
very heavy trains at those times. As the passengers 
must be distributed at many stations which are near 
together, it is necessary to stop often j and in order 
that the average speed may be reasonably fast the 
trains must run very rapidly between these stations. 
It is therefore necessary to have heavy locomotives, 
with more than the usual proportion of adhesive 
weight, so that the trains can be started quickly with- 
out slipping the wheels. The main valves should also 
have a liberal amount of travel, so that steam will be 
admitted to and exhausted from the cylinders quickly. 
In some cases it is thought desirable to have locomo- 
tives which will run equally well either way, so that 
it will not be necessary to turn them around at each 
end of the " run." 

By metropolitan railroads are meant railroads in 
large cities. They may be divided into two classes, 
one for carrying freight cars from the outskirts of 
cities to the warehouses and stores at their business 
centres, and also from the terminus of one road to that 
of another. Metropolitan railroads of this kind are 
usually branches of lines which extend from the city. 
Locomotives for such traffic must have great tractive 
power, in order to pull heavy trains, and as the speed 
is usually slow the wheels and the boiler capacity may 
be small. They must generally be capable of running- 
through curves of very short radius ; and as the traffic 
is usually carried through streets in close proximity to 
buildings, the locomotives should be as nearly as possi- 
ble noiseless. The other class of metropolitan roads 
is for carrying passengers. The traffic of the latter is 
37* 



438 Catechism of the Locomotive, 

similar to that usually carried on horse railroads, and 
consists almost exclusively of passengers. At present 
(1874) there are only one or two metropolitan rail- 
roads in this country for carrying passengers which 
are operated by steam power. It seems certain, how- 
ever, that their use will soon become very general in 
all large cities. Their traffic will consist of many 
light trains run at short intervals and at compara- 
tively slow speeds, and therefore very light locomotives 
are required. 

Question 439. What kinds of locomotives are used 
for suburban railroads'? 

Answer. The ordinary American eight- wheeled loco- 
motive is used more than any other kind ; but a num- 
ber of locomotives like that represented by fig. 222 
have been built and are used for this traffic. These 
have one pair of driving-wheels in front of the 
main pair and a Bissell truck in front of the cylin- 
der. With this arrangement the driving-wheels bear 
a larger proportion of weight than they do if arranged 
on the ordinary American plan with a four-wheeled 
truck. Another plan is that shown in Plate XVIII. 
Such engines, as will be seen, have a Bissell truck at 
each end, and therefore they run equally well either 
way. In some cases the tanks of such engines are 
carried on the top and sides of the boiler. When 
they are obliged to run only a short distance, and a 
small supply of water is needed, this arrangement an- 
swers very well ; but it is impossible to carry a large 
supply of water in this way without overloading the 
wheels of the locomotive, and at the same time in- 
creasing the evils of a varying load on the driving- 
wheels. 



440 



Catechism of the Locomotive. 



Locomotives like that shown in Plate XIV are also 
used for suburban traffic. As shown in the engraving 
they have a four-wheeled truck at one end and one 
with two wheels at the other, so that it is thought 
that they can be run safely either way. The four- 
wheeled truck carries the weight of the water and 
fuel. 

The plan of engine represented by Plate XV is very 
well adapted for this kind of traffic. Excepting on 
curves with a very short radius it could be run in 
either direction at any required speed, without encoun- 
tering any other difficulty excepting the prejudices of 
those who run it. 

As double-truck locomotives similar to that shown 
in Plate XVI can adjust themselves to any curve, this 
objection could not be urged against their use. 

Question 440. What hinds of locomotives are used on 
metropolitan railroads f 

Answer. For freight traffic ordinary switching loco- 
motives like that represented in Plate IV are often 
employed. In some cases these have the tanks on the 
locomotives. It often happens, though, that such 
traffic must be conducted in the streets of a city, and 
that the noise, especially of the exhausting steam, is 
thus liable to frighten horses and disturb the occu- 
pants. It is, then, necessary either to condense the 
exhaust steam or render its escape noiseless, which is 
done by allowing it to escape into the water-tanks. 
Street locomotives which have a condenser similar to 
the surface condensers used on marine engines are 
used on the Hudson River Railroad in New York. 
The exhaust steam passes through these and then es- 
capes into the tanks. The latter are long and nar- 



Different Kinds of Locomotives, 441 

row, so as to expose a great deal of surface to radia- 
tion, and in this way cool the water which becomes 
heated by the steam. The engines have four driving- 
wheels and vertical boilers. The cylinders are con- 
nected to a crank shaft with a pinion on it, which 
gears with another wheel of larger size on the driving- 
axle. In this way the speed is reduced and great 
tractive power can be exerted. The whole of the en- 
gine is enclosed so as to hide the machinery, the sight 
of which is supposed to frighten horses. The engines 
were designed and patented by Mr. A. F. Smith, for- 
merly Master Mechanic of that road. 

For roads in cities carrying passengers almost exclu- 
sively, an entirely different class of locomotives is 
needed. To suit passengers it is of course necessary 
to run a great many trains at very short intervals. 
When this is done the trains are necessarily very light, 
and therefore only light locomotives are needed. Plate 
XIX represents the locomotives employed on the 
Greenwich Street Elevated Railroad in New York. 
These engines weigh only 10,000 lbs., and the wheels 
are 30 in. diameter and the cylinders 7 X 10 in. The 
peculiarity in their construction consists in their hav- 
ing an intermediate shaft between the two pairs of driv- 
ing-wheels. This shaft has two cranks inside of the 
frames and two outside. The cylinders are connected 
to the inside cranks, and the coupling-rods to those on 
the outside. The water is carried in a tank on top of 
the boiler. The fuel is anthracite coal. 



PART XXIII. 
CONTINUOUS TRAIN BBAKES. 

Question 441. What are meant by automatic or con- 
tinuous train brakes ? 

Answer. Continuous train brakes are brakes which 
can be applied to all the cars of a train by the locomo- 
tive runner on the locomotive. In some cases such 
brakes are arranged in such a way that they can also 
be applied from any car in the train, or are made self- 
acting in case of an accident, such as a car getting off 
the track or a train breaking in two. 

Question 442. What are the principal systems of 
brakes of this kind in use ? 

Answer. What is called, after its inventor, the Wes- 
tinghouse atmospheric brake is now used more than 
any other. Next to this, Smith's vacuum brake is 
used most. Besides these two, Creamer's, Ward's, 
Loughridge's and Henderson's systems of brakes are 
used to a limited extent. The two first are, however, 
the only ones which have come into sufficiently exten- 
sive use as yet to justify us in describing them here. 

Question 443. How does the Westinghouse brake act 
and how is it constructed ? 

Answer. As its name indicates, the medium em- 
ployed for transmitting the power for operating the 
brakes is atmospheric air. 

This is compressed to any required density by a 



Continuous Train Brakes. 



443 



steam pump which is located hetween the driving- 
wheels, or in any other convenient place on the loco- 
motive. This pump is shown in section in fig. 223 
and consists of two cylinders, the upper one, A, the 
steam cylinder, the piston of which is connected by 
its rod with the piston in the lower cylinder, B. This 
latter is operated by the steam piston, and at each 




Fig. 223. Scale y 2 in.=l foot. 

stroke a quantity of air, equal to the space swept 
through \>y the lower piston, is compressed and thus 
forced into a cylindrical reservoir, which is usually 
placed under the foot-board of the locomotive, in which 
it is stored for use at any time when the brakes are to 
be applied. The air and steam cylinders are supplied 



444 Catechism of the Locomotive. 

with suitable valves for admitting and releasing the 
air and steam. From this reservoir it is conducted 
back under the tender and cars by pipes, which are 
connected together between the engine and tender and 
between the cars by India rubber hose. Two pieces 
of hose are attached to the engine and also to each end 
of the tender and cars, so that in case one piece should 
break the others will act. Each of these pieces is 
united or coupled to the corresponding piece opposite 
to it by a peculiar coupling made for the purpose, so 
that they can be quickly disconnected if the cars, en- 
gine or tender are uncoupled. 

Under the tender and also under each car is a cyl- 
inder and piston. The compressed air is conducted to 
this cylinder in front of the piston when the brakes 
are to be applied. As the piston-rod is connected by 
a bell crank to the brake levers when the piston is 
forced out by the pressure of the air, the brakes are at 
once applied to the wheels. As the reservoir under 
the foot-board is connected by the pipes which have 
been described with the cylinders under each car and 
the tender, by simply opening communication between 
the reservoir and the pipes, the air at once rushes from 
the reservoir back through the whole length of the 
train, and so rapid is its motion and quick its action 
that only a second or two intervenes between the 
opening of communication and the application of the 
brakes. To relieve or "let off" the brakes it is only 
necessary to close the reservoir cock and open commu- 
nication from the air-pipes to the external atmosphere, 
when the compressed air in the brake cylinders will 
escape, and the springs ordinarily used on car brakes 
will cause the pistons to resume their former positions. 



Continuous Train Brakes. 



445 



For the purpose of opening the connection from the 
reservoir to the brake cylinder, and closing this con- 
nection and opening one from the latter to the exter- 
nal air, a single three-way cock is commonly used. 
This is arranged at such a point as to be under the 
control of the engineer, so that he can at pleasure turn 




Kg. 224. Scale iy 2 inch=l foot 

on the compressed air with any degree of force, in- 
stantaneously, or slowly, or with a varying power, or 
by another turn of the cock let it off as freely, still 
keeping it under the same complete control. 
38 



446 



Catechism of the Locomotive. 



Question 444. How does the vacuum brake act and 
how is it constructed ? 

Answer. The power is applied to the brakes of the 
cars in this system by exhausting instead of compress- 
ing the air. This is done by means of an ejector, of 
which fig. 224 is a section. This operates somewhat 
like an injector. Steam is admitted into the pipe B, 
and escapes through the annular or circular opening 
a a. The effect of this is to create what is called an 
" induced current," or to draw the air from the pipe 
0" (7, which, with the steam, escapes at A. This pro- 
duces a partial vacuum in the pipe G, which ex- 
tends back under the cars. The pipes under the cars 
are connected together by rubber hose, which are pre- 
sented from collapsing by coils of wire inside. Under 
the tender and under each car are India rubber cylin- 
ders with cast iron ends, one fastened to the car and 
the other movable. The rubber cylinders can be ex- 
tended or compressed somewhat like the bellows of an 
accordeon. The rubber is supported by iron rings in- 
side, placed from 4 to 6 inches apart, so as to prevent 
them from collapsing when the air is exhausted from 
them. When this is done the pressure on the movable 
cast iron end draws it towards the fixed one, and by 
attaching the former to the brake levers by a rod, the 
force of the pressure on the head is communicated to 
the brakes. 

The ejector is placed on top of the boiler, and when 
the brakes are to be applied the locomotive runner 
opens a valve, which admits steam into the ejector, 
which instantly begins to produce a partial vacuum 
and thus apply the brakes. When the pressure of the 
brakes is to be released, the release valve, D, is opened, 



Continuous Train Brakes. 



447 



which admits air into the pipe, C, through which it is 
conducted back to each of the India rubber cylinders, 
and thus counteracts the pressure on the ends and re- 
leases the brakes. 

Both the atmospheric and the vacuum brakes have 
recently been applied to the driving-wheels of locomo- 
tives with very excellent results. 



PART XXIY. 



PERFORMANCE AND COST OF OPERATING 
LOCOMOTIVES. 

Question 445. What is the cost of operating ordinary 
locomotives per mile run ? 

Answer. The average cost at the present time (1874) 
is from 20 to 25 cents per mile.* 

Question 446. What items of cost are included in this, 
and what proportion do they each bear to the total cost f 

Answer. The items of cost and the percentage of 
each to the whole expense of operating locomotives, 
and also to the total of all the expenses of operating 
locomotives are given in the following table : 





t* «3 

OS ft 

lis 

las 
as a 

< 


Cm as 
"Sg Mm 

41 U C» 


Percentage of to- 
tal cost of all 
the operating 
expenses of 
railroads. 


Fuel 


6.0 cts. 


0.30 


.03 


Oil and waste 


0.4 cts. 


0.02 


.004 


"Wages of locomotive runners and firemen . 


6.0 cts. 


0.30 


.06 


Repairs of locomotives 


7.0 cts. 


0.35 


.07 


Cleaning locomotives 


0.6 cts. 


0.03 


.006 


Total 


20.Octs. 


1.00 


.20 



From this table it will be seen that the locomotive 



* Deducting 10 per cent, from this amount will give very nearly the 
gold value of the cost. The figures given above represent the cost in 
the depreciated promises to pay of the United States Government. 



Performance and Cost of Operating. 449 

expenses are 20 per cent, of the whole cost of operating 
railroads. This cost of course varies under different 
circumstances. The above is probably somewhat 
lower than the average cost in this country. 

Question 447. How many miles do locomotives ordi- 
narily run per ton of coal and per cord of wood ? 

Answer. This also varies greatly under different cir- 
cumstances. An average taken from the monthly re- 
ports of 52 different roads gives 38 miles run per ton 
of coal, and an average from the reports of 16 roads 
gives 47J- miles run per cord of wood. No deductions 
should, however, be made from this of the relative 
value of wood and coal for fuel, because the trains 
which are run with wood for fuel are usually lighter 
than those hauled with coal-burning engines. The 
above figures are the average results during the 
month of May, 1871, of all the trains on the roads 
from whose locomotive reports it has been compiled. 
The following report of experiments, which were care- 
fully made by the writer, will give the performance 
of a locomotive when great care is taken to produce 
good results. It should be stated, however, that the 
engine with which these experiments were made had 
been in service eighteen months, without receiving 
thorough repairs, and that the boiler at times primed 
badly, so that the rate of evaporation of water per pound 
of coal is not a fair indication of the performance of 
the engine in that respect. The coal used was known 
as Brazil coal, from Indiana, and in order to compare 
the performance of two engines only lumps of coal 
were used, so as to leave no room for question regard- 
ing the relative amount of fine coal used by each en- 
gine. The maximum grades on the road on which the 
38* 



450 Catechism of the Locomotive. 

experiments were made were 30 feet per mile, and 
the total ascent from the lowest to the highest point 
on the road was 374 feet. 

LOCOMOTIVE EXPERIMENTS. 



1873. 


1873. 


1873. 


July 21. 


July 28. 


August 2. 


145 


145 


145 


41 


31 


41 


1,497,240 


1,119,650 


1,508 860 


8,676 


5,102 


7,221 


63,531 


45,719 


52,609 


7.32 


8.02 


7 04 


33.4 


50 8 


38.8 


1.45 


1.13 


1.21 


11.1 


13 


13.8 



Date of experiment 

Number of miles run 

Number of cars hauled 

Total weight of cars, lbs 

Total amount of coal burned, lbs. . 
Total am'nt of water consumed, lbs 
Water evaporated per lb. of coal, lbs. 
Miles run per ton (of 2,000 lbs.) of coal 
Coal consumed per car per mile, lbs. 
Average speed, including stops, miles 

Question 448. How can we determine the speed at 
which an engine is running f 

Answer. In the absence of any special instruments 
for the purpose, by counting the number of revo- 
lutions OF THE DRIVING-WHEELS PER MINUTE, 
THEN MULTIPLYING THE LENGTH OF THEIR CIRCUM- 
FERENCE IN INCHES BY THE NUMBER OF THEIR REVO- 
LUTIONS PER MINUTE AND THE PRODUCT BY 60, AND 
DIVIDING THE LAST PRODUCT BY 63,360. THE QUO- 
TIENT WILL BE THE SPEED IN MILES PER HOUR. Thus, 

supposing driving-wheels which are 61-J in. in diame- 
ter, and whose circumference is therefore 193.2 in., 
should make 164 revolutions per minute, then 193.2 
X 164 X 60 -T- 63,360 =30, (nearly) miles per hour. 



PAET XXV. 
WATER-TANKS AND TURN-TABLES. 

Question 449. How are locomotive tenders or tanks 
supplied with water f 

Answer. At suitable points, called water stations, 
along the line of the road, large tanks or reservoirs are 




Fig. 225. Scale ^ in.=l foot. 

located, which are filled either from a natural stream 
which is higher than the tank and thus flows into 
the latter, or else the water is pumped in, either 
by hand or by horse, wind, water or steam power. 



452 



Catechism of the Locomotive. 



These tanks are usually, when there is room for thein, 
located near the track, as shown in fig. 225, so that the 
water can be conducted by a spout, a, direct from the 
tank to the man-hole of the tender. Communication 
to and from this spout is opened and closed by a valve, 
b, inside of the tank. The spout is usually attached 
to the tank by a hinged joint, so that it can be low- 
ered to the tender and then raised up out of the way 
of the engine and train. It is generally balanced by 
a counterweight, suspended to one end of a rope, 
which passes over a pulley and is fastened to the spout 
at the other end. Such tanks are now generally made 
of wooden staves like a tub or pail, and supported on 
a heavy frame, c c c, made of wood, as shown in the 
engraving, or on stone or brick masonry. 




- Fig. 226. Scale ^ in.=l foot. 

When there is no room for the tank or reservoir 
near the track, it is placed in any convenient position 
at some distance from it, and the water is then con- 
veyed by an underground pipe to the place where the 
locomotive must take water. At the end of this pipe 
what is called a water-crane, fig. 226, is located. This 
consists of a vertical pipe, A, with a horizontal arm, 
B, which is made so as to swing around over the man- 
hole of the tender when the latter is to be filled with 



Water- Ta?iks and Turn- Tables. 453 

water. In some cases the horizontal arm alone swings 
around, hut in others the vertical pipe turns with the 
horizontal one in a joint, C, underneath the surface of 
the ground. The latter plan is thought to be prefera- 
ble to the first, as the pipe is less liable to freeze fast 
in the joint when the latter is underground than when 
it is exposed above. A suitable valve, D, is also at- 
tached to the pipe below ground, so that the stream of 
water can be turned off or on at pleasure by the 
wheel E. 

Question 450. What considerations should determine 
the source from which a supply of water should be 
drawn ? 

Answer. The first must of course be its convenience 
to the point where the water is to be used ; but more 
attention should be given to the quality of the water 
than it ordinarily receives, as the use of impure 
water, or that which contains a considerable amount 
of mud or solid matter mixed with it, or in suspen- 
sion as it is called, or has lime or other mineral sub- 
stances chemically combined with it, will very soon 
coat the inside of the boiler with a covering of scale, 
which is a very bad conductor of heat, and conse- 
quently the boiler is much less efficient and much 
more heat is wasted than if the heating surfaces were 
clear. Besides this loss of efficiency, when boiler 
plates are covered with non-conducting scale, they 
are much more liable to be injured by the action of 
the fire than when the water comes directly in contact 
with the metal of the plates. Some water, too, has a 
corroding effect on the metal of the boiler which is very 
destructive. 

Question 451. How can the relative amount of in- 



454 Catechism of the Locomotive. 

crustating substances in different hinds of water be deter- 
mined'? 

Answer. The relative quantity of solid matter or mud 
which is held in suspension can be at least approxi- 
mately determined by simply filling vessels, say large 
clear glass bottles, with different kinds of water and 
letting them stand for some time until the solid matter 
settles to the bottom. 

An easy method of precipitating the lime and some 
other salts which are held in solution and which will 
not settle until they are converted into a solid form is 
the following : Dissolve in a goblet of pure water (dis- 
tilled or freshly caught rain water) two or three tea- 
spoonfuls of the oxalate of ammonia. Have equal 
quantities, say a goblet-full of each of the waters to be 
tested, ranged side by side and marked so as to be 
identified. Into each of these goblets stir equal quan- 
tities of the solution mentioned — about three tea- 
spoonfuls will be enough — and let them stand for a 
day. The lime and some other salts will be precipi- 
tated and fall to the bottom as a powder ; and the 
quantity of this precipitate in each glass will form a 
very good index of its relative injuriousness in the 
formation of scale. 

When the oxalate of ammonia cannot easily be pro- 
cured, an experiment may be tried, in the same way, 
by dissolving common white soap, or other pure soap, 
in a goblet of pure water, and then stirring into the 
glasses of water to be tested a few teaspoonfuls of this 
solution. The comparative amount of lime in the 
water will be shown by the amount of coagulated mat- 
ter which will be thrown down.* 



* Correspondent of the Railroad Gazette. 



Water- Tanks and Turn- Tables. 455 

Question 452. How are locomotives turned around 
on the track ? 

Answer. The most common means employed for 
that purpose is a turn-table, fig. 227. This consists of 
two heavy beams made of wood, cast or wrought iron, 
placed side by side and resting on a pivot in the cen- 
tre, on which they turn. They are placed in a circular 
pit below the level of the track, so that when rails are 
laid in the ordinary way on top of the beams they will 
be exactly level with the track which leads up to the 
pit. By turning the beams on the central pivot so 
that the rails will come exactly in line with the per- 
manent track which leads up to the pit, the locomo- 
tive can be run on the turn-table, which is then re- 
volved a half-revolution, which of course reverses 
the position of the locomotive and brings it opposite 




Fig. 228. Scale -jfe in. =1 foot. 

the permanent track so that it can be run off from the 
table. In order to prevent the beams from tipping 
down when the engine first runs on or off of the turn- 
table, wheels are placed at their outer ends which run 
on a circular track and bear any inequality of weight 
that may be thrown on them if the locomotive is not 
equally balanced on the central pivot. 

Question 4.5-3. How is the central pivot constructed? 



458 Catechism of the Locomotive. 

Answer. It usually consists of a vertical post, A, 
shown in fig. 228, which is a transverse section through 
the centre of the turn-table, the end of which rests on 
hard cast iron or steel bearings. In some cases, as 
shown in figs. 227 and 228, which represent a turn- 
table built by William Sellers & Co., of Philadelphia, 
the weight rests on conical steel rollers, m m, which 
revolve in a circular path formed in the top plates. 
Sometimes turn-tables are fitted with gearing and 
cranks, D, fig. 228 ; but if they are made so that the 
whole weight rests on the centre, and if they are of 
sufficient length so that an engine and tender can be 
moved on them sufficiently to be balanced over the 
centre, gearing will not be needed ; but a simple lever 
fastened to the turn-table will be all that will be re- 
quired to turn the table and the engine and tender 
on it. The tables should be of such a diameter or 
length across the centre as will enable the class of en- 
gine in use on any road to be balanced. With light 
engines the 50-feet table is large enough ; with the 
long, heavy engine now used on the great trunk lines, 
the engine and tender quite fill up the entire length 
of 50 feet, leaving no margin for adjustment. In such 
cases, the 54 feet, 56 feet, or, better, the 60 feet, should 
be employed. These large tables are also made heavier 
in proportion. The table should be of such a length 
that engines, with tender either empty or full, when 
run on the table can be so placed as to bring the cen- 
tre of gravity immediately over the centre. When so 
balanced, one man can turn the loaded table with ease. 

In setting up turn-tables it is necessary that the 
foundation at centre, upon which the pivot rests, 
should be of the most substantial character, so as not to 



- Water- Tanks and Turn-Tables. 459 

be liable to settle. The circular track, which may be 
made of light rails, say 28 or 30 lbs. to the yard, 
should be level, and the table should be so adjusted as 
to swing clear of the circular track when loaded. The 
pit required is quite shallow near the edge and deep- 
ens towards the centre. Provision is made for cover- 
ing the entire pit by a platform turning with the 
table, but this should be avoided whenever possible, 
as the best constructed cover does offer some resist- 
ance in turning. Even in roundhouses, where a cov- 
ered pit might be considered preferable as presenting 
a smooth floor for crossing in any direction, it has 
been found advisable, in view of the greatest ease 
in turning and the facility offered by the open pit for 
cleaning, to dispense with the cover. The centre 
upon which the table turns is constructed of the best 
cast steel, and consists of conical rollers of steel be- 
tween two steel plates grooved out to receive these 
rollers. This part of the table must be kept clean and 
well oiled, say with best sperm or lard oil and tallow 
of such a consistency as not to harden in cold weather. 
The top cap at centre is held in place by a circle of 
bolts. These bolts take the entire weight of the table 
and load ; by slacking off the bolts the table can be 
lowered on the wheels on the circular track and the 
cap lifted off to gain access to the plates and rollers. 
These should be opened, examined and cleaned at 
least once every three months.. 

Under the cap and between it and the top of the 
centre box are segments of wood. These can be al- 
tered in thickness to bring the table in proper adjust- 
ment. If the centre foundation settles, these segments 
should be thinned sufficiently to enable the table to 



460 Catechism of the Locomotive. 

be screwed up to a proper height. With proper care 
such tables are practically indestructible.* 

Question 454. Is there any other method of turning 
locomotives ? 

Answer. Yes ; what is called a Y is sometimes used. 
This consists of a system of tracks laid somewhat in 
the form of the letter Y, as shown in fig. 229, in which 
A B is the main track, with two curves, A Candi? C, 
laid as shown. If now it is desired to turn a loco- 
motive which is standing in the position of the dart 
A, it is run on the curve A G to the position of the 
darts a and C. It is then run backward from G on the 
curve C B, as represented by the dart b, and when it 
reaches the main track in the position of the dart B 
it is evident that its position will be reversed, as is 
shown if we compare the direction of the dart A with 
that of B. 



*Wm. Sellers S Co. 



PART XXYI. 
INSPECTION OF LOCOMOTIVES. 

Question 455. What are the principal divisions of 
the work of operating or running a locomotive ? 

Answer. They are : 1. Inspection and lubrication ; 
that is, an examination of the parts to see that they 
are in good working order, and the application of oil 
to the journals and other parts subjected to wear. 2. 
Setting the engine in motion and starting the locomo- 
tive and train. 3. Management while running. 4. 
Stopping the engine and train. 5. Laying up. 6. 
Management in case of accident. 7. Cleaning the en- 
gine. 

Question 456. When the locomotive is inspected, what 
should be especially observed about the boiler f 

Answer. In the first place, all new boilers should be 
tested by pressure before being used, and all boilers, 
whether new or old, should be tested period- 
ically. The oftener the better. The ways of apply- 
ing the pressure test are : 1, the cold-water test, that 
is, by filling the boiler with cold water and then forc- 
ing in an additional quantity with a force-pump so as 
to raise the pressure to that at which it is intended to 
test the boiler ; 2, the warm-water test, by filling the 
boiler entirely full of cold water and then kindling a 
fire in the grate so as to warm this water. As water 
expands about one twenty-fourth in rising from 60 to 



462 Catechism of the Locomotive, 

212 degrees, the rise in temperature will cause a cor- 
responding increase in pressure ; 3, by steam press- 
ure. 

If the latter method were not so commonly used, it 
would seem the height of madness to test a boiler — 
which is neither more nor less than an attempt to 
explode it — in the shop where it is built or repaired, 
and where the results of an explosion would be more 
disastrous and fatal than anywhere else, in order to 
see whether it will explode when put into service 
on the line of the road. The danger of explosion is 
also increased at such times by hammering and caulk- 
ing at leaky rivets and joints.* It would seem, there- 
fore, very much more rational to test boilers first by 
hydraulic pressure. For a first test this is preferable, 
because cold water will leak through crevices which 
would be tight when the boiler is heated, so that leaks 
can be more surely detected with cold than with warm 
or hot water. It is, however, doubtless true that boil- 
ers are often strained much more by the unequal ex- 
pansion of the different parts than by the actual press- 
ure. It is therefore thought that after the hydraulic 
. test has been applied the second or warm-water test 
should be used. This can be easily done, as the boiler 
must be filled full of water for the first test. When 
the boiler is subjected to the test pressure, it should 
be carefully examined to see whether any indications 
of weakness are revealed. Any material change of 
form or any very irregular change of pressure is in- 
dicative of weakness. The flat stayed surfaces should 
be carefully examined by applying a straight edge to 
them before and after they are subjected to pressure, 



* Wilson on Boiler Construction. 



Inspection of Locomotives, 463 

to see whether they change their form materially. One 
of the greatest dangers and most common accidents to 
locomotive boilers, as has been pointed out in a previ- 
ous chapter, is the breaking of stay-bolts, to detect 
which, a locomotive runner and master mechanic 
should exercise constant vigilance. While the press- 
ure is on, the outside surface of the boiler should be 
thoroughly examined with slight blows of a hammer, 
which will often reveal a flaw in the metal or a defect 
in workmanship. After the hydraulic and warm- 
water tests have been applied, the boiler should be 
emptied, and the inside examined carefully to see 
whether any of the stays and braces have been broken 
or displaced by the test. After this has been done, 
and not until then, should steam be generated in the 
boiler. In making the latter test it would doubtless 
be more safe to employ a pressure somewhat lower 
than that employed with the cold and warm water. 
There is great diversity of opinion regarding the max- 
imum pressure which should be employed in testing 
boilers. It is doubtless true that a weak boiler might 
be injured and thus made dangerous by subjecting it 
to a very severe pressure, while without such a test it 
would have been safe. Recent experiments have in- 
dicated, however, that in most cases the ultimate 
strength of material is actually increased by subject- 
ing it to a strain which even exceeds the elastic limit, 
provided such a strain is imposed only a few times. 
Although no absolute rule can be given to govern all 
such cases, it is thought that for the hydraulic and 
warm- water tests, a pressure about 50 per cent, greater 
and for the steam test 25 per cent, greater than the 
maximum working pressure should be employed. 



464 Catechism of the Locomotive. 

Before old boilers are tested, they should be very 
carefully examined, both inside and outside, to see 
whether they are injuriously corroded. It is to be 
regretted that the insides of locomotive boilers are 
usually made so difficult of access that it is impossible 
to discover the extent and the effects of corrosion 
without the most careful examination. This is 
not possible without getting inside of the boiler. 
Whenever this can be done, a prudent locomotive run- 
ner should use the opportunity of inspecting the boiler 
of his engine himself, and not depend upon the boiler- 
makers who are employed for that purpose. He 
should remember that it is his life and not theirs 
which is exposed to danger by any weakness or defect 
in the construction of the boiler of the locomotive 
which he runs. 

Before starting the fire in a locomotive, the fire-box 
should be carefully examined to see if there are any indi- 
cations of leaks, which will often reveal cracked plates, 
defective stay-bolts or flues. If the latter simply leak 
at the joints, they can generally be made tight by 
caulking or the use of the tube expander. This is 
easily done when the engine is cold, but if not at- 
tended to may be very troublesome on the road. Leaks 
at other parts of the boiler should be examined, as 
they may reveal dangerous fractures. 

It is of the utmost importance, both for safety and 
for economy of working, that boilers should be kept 
clean, tha^t is, free from mud and incrustation. In 
some sections of the country, especially in the Western 
States, this is the greatest evil against which locomo- 
tive runners and those having the care of locomotives 
must contend. The cures which have been proposed 



Inspection of Locomotives, 465 

are numberless, but that which is now chiefly relied 
upon is, first, the use of the best water that can be 
procured, and second, frequent and thorough washing 
out of the boiler. 

Question 457. What sort of examination should be 
given to the boiler attachments ? 

Answer. It should be observed whether the grate- 
bars or drop-doors of the grate are properly fastened, 
and whether the ashes have been cleaned out of the 
ash-pan, and also whether the fire is clean, that is, 
whether the grates are free from cinders or clinkers. 
The height of water in the boiler should be observed 
by testing it with the gauge-cocks and by noticing it 
in the glass gauge, if one of the latter is used. It is 
also well to blow out the sediment and mud from the 
latter before starting, and to see that the valves which 
admit steam and water to the glass are open. They 
should, however, be opened only a very short distance, 
so that only a small quantity of steam or hot water 
will escape in case the glass tube should be broken. 
The injector, if one is used, should be tested to see 
that it is in working order, and as soon as the engine 
starts out of the engine house both of the pumps 
should also be tested, in order to see whether they are 
in good working condition. The safety-valves should 
be raised, so as to be sure that they are not rusted or 
otherwise fastened to their seats. There is no part of 
a locomotive more liable to disorder than the steam 
gauge. For this reason it should be frequently tested, 
and whenever there is any indication of irregularity 
in its action it should, be examined. As the wire net- 
ting on the smoke-stack often has holes cut into it by 
the action of the sparks, it ohould be frequently ex- 



466 Catechism of the Locomotive, 

amined to see whether it is in good condition. It is 
also liable to be "gummed up," especially if too much 
oil is used in lubricating the cylinders and valves. As 
soon as holes are cut into the netting there is danger 
that the sparks which escape will set fire to the com- 
bustible material near the track, and if the netting 
is gummed up the draft will be obstructed and the en- 
gine will not make steam. The gummy matter can 
often be removed by building a wood fire on top of the 
netting. In this way the oil in the gummy matter is 
burned up, which leaves a dry material which can 
then, at least to some extent, be beaten out of the 
netting. 

Question 458. How can it be known whether the 
pumps are working well? 

Answer. Their operation is indicated by the force of 
the stream which escapes from the pet-cock when it is 
open. When the pump is in good condition the water 
begins to escape promptly in a strong stream as soon 
as the pump-plunger begins its inward stroke, and 
continues to escape until the plunger completes its 
stroke. If the pump is not in good condition, this es- 
caping stream is weak and is apt to continue during 
the outward stroke of the pump-plunger. It is diffi- 
cult to tell, however, when the engine is running 
slowly, whether the pump will work well at higher 
speeds, and therefore a locomotive runner should al- 
ways test the condition of the pumps during the pre- 
vious run. 

Question 459. What should be noticed in connec- 
tion with the throttle-valve ? 

Answer. As a failure of the throttle- valve to work 
may be the cause of a most serious accident, it should 



Inspection of Locomotives. 467 

be certain that it is in good working condition, that 
all the bolts, pins and screws and other accessories are 
in good working order. It should also be known 
whether the throttle-valve is steam-tight. This can 
be learned by observing whether steam escapes from 
the exhaust-pipes or cylinder-cocks when the latter 
are open, the reverse lever in full gear, and the 
throttle-valve closed. If the throttle-valve leaks, 
enough steam may accumulate in the cylinder, when 
there is no one on the engine, to start it, and in this 
way cause a serious accident. The throttle-lever 
should always be fastened with a set-screw or latch of 
some kind when the engine is standing still. 

Question 460. In inspecting the cylinders, pistons, 
guides and connecting-rods, to what points should the at- 
tention he directed? 

Answer. It should be known whether the piston 
packing is properly set out, that is, whether it is so 
tight that it will not "blow through" or leak steam 
from one end of the cylinder to the other, which of 
course will waste a great deal of steam. Of the two 
evils, it is, however, better to have piston-packing too 
loose than too tight, because if it is too tight, it is li- 
able to cut or scratch the cylinders so as to make it 
necessary to rebore them, and at the same time if the 
packing-rings are lined with Babbitt metal, the heat 
created by the intense pressure and friction will melt 
the metal. In some cases the cylinders become heated 
to so high a temperature from this cause that the 
wood-lagging with which they are covered on the out- 
side is burned. 

The packing of the piston-rods should be steam- 
tight, and it should be observed whether the rod and 



468 



Catechism of the Locomotive. 



the pump-plunger are securely attached to the cross- 
head. 

The utmost care must be exercised to keep the 
guides well oiled. The oil cups on the guide-rods or 
cross-heads, when they are placed on the latter, must be 
kept clean, so that the oil will flow freely, and yet not 
too rapidly, on the surfaces exposed to friction. The 
same thing is true of the oil-cups on the connecting- 
rods. Attention should be given to the brass bearings 
of the connecting-rods to see that they are not so loose 
as to thump, nor keyed so tight on the crank as to be 
liable to heat. The latter can be easily known by 
moving the stub-end lengthwise of the journal. They 
should never be so tight that they cannot be thus 
moved with the hand. Especial attention should be 
given to seeing that all the bolts and nuts on the con- 
necting-rods are tight. There are no parts of a loco- 
motive which require more careful attention in order 
to keep them lubricated, and thus prevent them from 
heating and being "cut," than the bearings on the 
crank-pins and the slides of the cross-head. Examin- 
ation should be made to see that neither the pis- 
ton-rods, pump-plungers, guides, connecting-rods nor 
crank-pins are bent or sprung. 

Question 461. How can it be known ivhether the 
piston-packing is too loose or " blows through ? " 

Answer. It can usually be noticed in the sound of 
the exhaust, which can be heard very distinctly on the 
foot-board when the furnace door is opened. If the 
packing is not tight, it produces a peculiar wheezing 
sound between and after each discharge of steam. If 
the packing leaks, it will also be indicated by the es- 
cape of steam from both the cylinder-cocks, if they are 



Inspection of Locomotives. 469 

open, just after the crank passes the dead point. This 
will usually show in which of the cylinders the pack- 
ing is too loose. The same thing will occur, however, 
if either or "both of the main valves leak, so that it is 
ofteu hard to determine whether the " blow " is due to 
a leak from the valve or from the piston. Of course, 
it may sometimes happen that both leak, or that the 
piston on one side and the valve on the other leak, so 
that often the diagnosis of the disease, as the doctors 
say, is extremely difficult. Careful observation and 
experience will, however, aid a locomotive runner in 
detecting such defects much more than any directions 
which can be given here. 

Question 462. What is meant by il setting out pack- 
ing" and how should it be done? 

Answer. u Setting out packing " is simply expand- 
ing the rings when they get too loose. With ordinary 
spring packing, figs. 96 and 97, which is now gener- 
ally used, this is done by screwing up the nuts b, b, b, 
which, as was explained in answer to Question 169, 
compresses the springs a, a, a, and thus expands the 
rings A, A. In doing this, as already stated, great 
care must be exercised not to screw the nuts up too 
hard, and it is always better to have the packing too 
loose than too tight. Care must also be taken to keep 
the piston-rod in the centre of the cylinder, otherwise 
there will be undue pressure and wear on the stuffing- 
box. After the nuts are screwed up, the position of 
the piston-head should be tested with a pair of calli- 
pers. This is done by placing one leg of the callipers 
against the side of the cylinder, and setting them so 
that the other leg will just touch the edge of the pro- 
jection E, fig. 96, or the end of the piston-rod. Then 
40 



470 Catechism of the Locomotive, 

by placing the callipers above and below, and on each 
side of the piston, it will appear whether it is too high 
or too low or too near either side ; then by loosening 
the nuts on one side and tightening them on the other 
it can be moved to a central position. Ordinarily this 
work is intrusted to persons who are employed for the 
purpose. A young locomotive runner, fireman or me- 
chanic will, however, always do well to familiarize 
himself with such duties, and, if possible, do it him- 
self, under the direction of those who are skilled in 
that kind of work. 

Questiox 463. If the stuffing-box of the piston-rod 
leaks, what should be done ? 

Answer. If the packing in it is in good condition, 
it can usually be made tight by simply screwing up 
the gland. In doing this, the nuts on the bolts should 
not be screwed up more than is necessary to make the 
packing steam-tight. Any greater pressure only in- 
creases the friction on the piston-rod unnecessarily. 
In doing this, the two bolts must be screwed up 
equally, otherwise the gland will be " canted," that is, 
inclined so as to "bind " or bear unequally and very 
hard against the piston-rod, and thus be liable to cut 
or scratch it. After packing has been in the stuffing- 
box a long time, it becomes very hard and compact, 
and sometimes partly charred. Then either it must 
be removed and new packing be put in, or, if in tol- 
erably good condition, it can often be made to work 
well by simply reversing it, that is, by putting that 
which was at the bottom of the stuffing-box on top 
and vice versa. Before packing is put into a stuff- 
ing-box, the former should always be thoroughly 
oiled 



Inspeetioyi of Ijocomocwes. 471 

Question 464. When the slides of the cross-heads 
wear, how is the lost motion taken up ? 

Answer. When there are gibs on the cross-head, 
the lost motion can be taken up by putting " liners " 
or " shims," that is, thin pieces of metal, between them 
and the cross-head, so that they will fill up the space 
between the guide-bars. When there are no gibs, the 
guide-bars must be taken down, and the blocks be- 
tween them at each end must be reduced in thickness 
so as to bring the bars nearer together. In doing this, 
great care must be taken that the guides are accu- 
rately " in line " with the centre line or axis of the 
cylinder. This work should never be intrusted to any 
excepting skilled workmen, from whom those who are 
inexperienced should seek instruction. 

Question 465. When the brass hearings of the con- 
necting-rods become too loose on their journals, what should 
be done f 

Answer. They must be taken down, and the two 
surfaces in contact must be filed away so as to bring 
them closer together. In doing this they must be 
filed square with the other surfaces, otherwise they 
will not bear equally on the journals when they are 
keyed up. Before attaching them permanently to the 
rods, they should be keyed on the journal in the strap 
alone, so that it can be known by trial whether they 
move freely and yet are tight enough to prevent 
thumping on the journal. When they are attached to 
the rod, it is very important, especially with coupling 
or parallel-rods, that the correct length from centre to 
centre of the bearings be maintained. It is much bet- 
ter to leave coupling-rods loose on their journals, be- 
cause, if the bearings are keyed up tight, the rods are 



472 Catechism of the Locomotive. 

sure to throw an enormous strain on the crank-pins, 
as the distance between the centres of the axles is not 
always absolutely the same, owing to the rise and fall 
of the axle-boxes in the jaws. It is therefore always 
best to have a little play in the coupling-rods, and it 
is safe to say that much more mischief is done by med- 
dling with the coupling-rod brasses than by neglect- 
ing them. 

Question 466. What part of the valve gear should 
receive attention when the engine is inspected? 

Answer. All the bolts, nuts and keys should be care- 
fully examined to see that t\\Qj are properly fastened. 
The bolts and nuts in the eccentric straps are espec- 
ially liable to become loose, and as they are between 
the wheels, and therefore not easy of access, are often 
neglected. The oil-holes should all be seen to be clear, 
otherwise it will be impossible to keep the journals 
well oiled. The eccentric straps and the link blocks 
are very liable to be imperfectly oiled, and when the 
former become dry and cut, they throw a great strain 
on the eccentric-rods, which is liable to break them. 
When this occurs the strap and the portion of the rod 
which is attached to it revolve with the eccentric, and 
frequently a hole is thus knocked into the front of the 
lire-box, which disables the engine. The valve gear 
is, with the exception, perhaps, of the pumps and in- 
jector, the most delicate part of the locomotive, and 
more liable to get out of order than any other, and 
should therefore be watched with the greatest care. 

Question 467. How can it be known whether the main 
valves of a locomotive are tight ? 

Answer. As already indicated, the symptoms which 
manifest themselves when a valve leaks are very sim- 



Inspection of Locomotives. 473 

ilar to those which appear when the piston packing 
leaks. If the valve is moved to its middle position 
and steam is admitted into the steam-chest, and it 
then escapes from both cylinder-cocks, it is apparent 
that the valve is not tight. But the valve faces of 
locomotives usually wear concave, because the valves 
are worked most about half-stroke, so that they will 
often be tight when in the centre of the face, but will 
leak at the ends of the full stroke. This will become 
apparent by the peculiar wheezing sound, already re- 
ferred to, when the engine is at work. As has been ex- 
plained, it is, however, often very difficult to determine 
whether this sound is due to a leak at the pistons or 
the valves. If the packing of the valve-stem leaks, it 
can be remedied in the manner described for making 
that of the piston-rod tight. 

Question 468. To what points of the running gear 
should attention be directed during inspection ? 

Answer. All the wheels of the engine and tender 
should be carefully examined to see that they are 
sound. A fracture in a driving-wheel is usually appar- 
ent if the wheel is carefully examined. The condition of 
ordinary cast iron tender and truck-wheels is revealed 
on striking them with a hammer, when if they are 
sound they will give out a peculiar clear ring; whereas 
if they are fractured, the sound produced by the blow 
of the hammer will be dead, like that of a cracked bell. 
The flanges of the wheels should also receive attention 
to see that they are not broken, as such a fracture is not 
always revealed by the sound produced by a blow from 
a hammer. The axles too should be examined to see 
that the wheels have not worked loose on the wheel- 
seat. When this occurs it often becomes apparent by 
40* 



474 Catechism of the Locomotive. 

the oil from the axle-boxes working through between 
the hubs of the wheel and the axle. This can be ob- 
served on the outside of the wheels when the bearings 
are inside, and inside the wheels when the bearing 
is outside. 

The springs should be examined to see that they 
are in good condition, and the oil-holes in the boxes 
must be kept clear, so that the oil can reach the bear- 
ings. The tender boxes are kept oiled by packing 
them with cotton or woolen waste saturated with oil. 
This should be taken out occasionally and renewed 
and the boxes cleaned. The working of the driving- 
boxes up and down the jaws will in time wear them 
so that there will be some lost motion in the jaws. 
This will be indicated by a thump when the cranks 
pass the dead point. A similar thump will, however, 
be produced by lost motion in the boxes of the main 
connecting-rod, so that it is difficult to determine, 
without special examination, the cause which produces 
the concussion. It is therefore best when an engine 
works with a thump at each revolution for the runner 
to stand by the side of it where he can touch the con- 
necting-rods and driving-wheels, and then have the 
fireman open the throttle-valve so as to move the en- 
gine slowly. If the lost motion is in the connecting- 
rods it can be felt by the jar as it passes the dead 
points. The same is true of lost motion in the jaws, 
which can be felt by touching the driving-wheels. 
When the jaws become worn the lost motion can be 
taken up by moving up one or both of the wedges. 
When this is done, great care must be taken to keep 
the centres of the driving-axles the same distance 
apart on both sides of the engine, and also to keep 



ion of Locomotives. 475 

their centre lines square with the frames. There 
should always be centre-punch marks placed on the 
frames or guide-yokes on each side of the engine in 
front of the main axle, and at equal distances from its 
centres, so that when the boxes or jaws become worn 
the position of the axle can be adjusted with a tram 
from these marks. Of course, if the main axle is 
square, it is easy to adjust the trailing axle from it 
with a tram. If the axles are not square with the 
frames and parallel with each other, the engine will 
run towards one side or the other of the track, accord- 
ing to the inclination of the axles. It sometimes 
happens that the bolts which hold up the wedges in 
the jaws are broken. When this occurs the wedge 
drops down, and of course the box has so much lost 
motion that it soon manifests itself in the working of 
the engine. These bolts, and also those which hold 
up the clamps on the frames at the bottom of the jaws, 
should be examined when the engine is inspected, so 
as to be sure they are in good condition. The bolts 
and nuts about both the engine and tender trucks 
should be watched to see that none are lost or work 
loose. The engine and tender should occasionally be 
lifted up from the centre plates of the truck, and the 
latter be lubricated with tallow. It often happens 
that these become dry, so that they are difficult to 
turn when the weight rests on them, and therefore 
they will not adjust themselves easily to the curves of 
the track. 

Question 469. What other parts of a locomotive 
should be examined before starting ? 

Answer. It should be certain that the brakes on the 
tender are in good working condition, that is, that the 



476 Catechism of the Locomotive. 

bolts, nuts and keys are all secure, the levers, rods 
and chains properly connected, and the shoes fastened 
and not too much worn. If either an atmospheric or 
vacuum brake is used, it should be tested before start- 
ing, to see that the pump or ejector is in good work- 
ing condition. It is also well to apply the brakes to 
the train before starting, so as to see whether the con- 
nections are in good condition and properly connected. 
It is always best for the locomotive runner to examine 
the connections of the brake hose through the whole 
tiain himself, to be sure that they are properly made. 

The inside of the water-tank should also be examined 
occasionally, to see whether it is clean, and if not it 
should be thoroughly washed out. The man-hole 
should always be covered before starting, in order to 
prevent cinders and coal from falling in, which are 
liable to obstruct the pump valves. It is hardly nec- 
essary to say that it must always be certain before 
starting that there is enough water in the tank to feed 
the boiler until the next point is reached at which a 
supply can be obtained. The sand-box must also be 
filled, the bell rope in good condition, and if running 
at night the reflector of the head-light must be pol- 
ished and the lamp supplied with oil and the wick 
trimmed so as to burn brilliantly. The locomotive 
runner must also see that the proper signals are dis- 
played in front of his engine. 

Question 470. What tools, etc., should every locomotive 
runner on the road carry ? 

Answer. A coal shovel, coal pick, long-handled hoe* 
and poker, a pair of jacks, either screw or hydraulic, 
chains, rope and twine to be used in case of accident, 



♦These are of course not needed on wood-burning engines. 



Inspection of Locomotives. 411 

a heavy pinch-bar for moving the engine, a small 
crow-bar, oil- cans with short and long spouts and an- 
other smaller one with spring bottom, a steel and a cop- 
per hammer, a cold and a cape chisel, a hand-saw, axe 
and hatchet, one large and one small monkey-wrench 
and a full assortment of solid wrenches for the bolts 
and nuts of the engine, cast iron plugs for plugging 
tubes, with a bar for inserting them, two sheet iron 
pails or buckets, different colored lanterns and flags, 
according to the colors used for signals on the line, 
and a box with a half-dozen torpedoes. 

Question 471. What duplicate parts should be carried 
with the engine ? 

Answer. Keys, bolts and nuts for connecting-rods, 
split-keys, wedge bolts, bolts for oil-cellars of driving 
and truck boxes, driving and truck spring-hangers, 
wooden blocks for fastening guides in case of accident, 
blocks for driving-boxes and links, a half-dozen j-in. 
bolts, from six inches to two feet long, to be used in 
case of accident, two extra water-gauge glasses, two 
glass head-light chimneys. 

Question 472. What should be observed in lubricating 
a locomotive or any other machinery ? 

Answer. The most important thing to observe is 
that the oil reaches the surface to be lubricated. It 
is of much greater importance that the lubricant 
should reach the right place than that a large quan- 
tity should be used. A few drops carefully introduced 
on a journal will do much more good than a large 
quantity poured on the part carelessly. For this reason 
all oil-cups and oil-holes should be kept clean so as to 
form a free passage for the oil. 



PART XXVII. 
EUNNING LOCOMOTIVES. 

Question 473. Before starting the fire in a locomotive^ 
what must he observed ? 

Answer. It must always be noticed, before kindling 
the fire, whether the boiler has the requisite quantitj'- 
of water in it; that all cinders, clinkers and ashes 
are removed from the grates and ash-pan ; that the 
grates and drop-door are properly fastened, and that the 
throttle-valve is closed and the lever secured. Loco- 
motive boilers are sometimes seriously injured by 
building a fire in them when there is no water in the 
boiler. In filling a boiler it must be remembered, 
however, that when the water is heated it will expand, 
and that when bubbles of steam are formed they will 
mix with the water and thus increase its volume, so 
that after the water is heated its surface will be con- 
siderably higher than when it is cold. 

Question 474. How should the fire in a locomotive be 
started ? 

Answer. It should be started very slowly, so as not 
to heat auy one part suddenly. Probably the greatest 
strains which a locomotive boiler has to bear are those 
due to the unequal expansion and contraction of its dif- 
ferent parts. When the fire is started, of course the 
parts exposed to it are heated first, and consequently 
expand before the others. Now, if the fire is kindled 



Running Locomotives. 479 

rapidly, the heating surfaces will become very hot before 
the heat is communicated to the parts not exposed to 
the fire. Thus the tubes, for example, will be ex- 
panded so as to be considerably longer than the 
outside shell of the boiler, and therefore there will be 
a severe strain on the tube-plates, which will be com- 
municated to the fire-box, stay-bolts, braces, etc. 
The inside plates of the fire-box will also become 
much hotter than those on the outside, and as it is rig- 
idly fastened to the bar to which both the inside and 
the outside shells are fastened at the bottom, its ex- 
pansion will all be upward, which thus strains the stay- 
bolts in that direction. As the motion due to this ex- 
pansion is greatest near the top of the fire-box, the 
top stay-bolts are of course strained the most, and it 
is those in that position, as has already been pointed 
out, which are the most liable to break. When steel 
plates are used the expansion or contraction often 
cracks them, and sometimes, hours after the fire is 
withdrawn from the fire-box, the inside plates will 
crack with a report like that of a pistol. It is there- 
fore very important both to heat and cool a locomotive 
boiler very slowly, and the fire should always be kin- 
dled several hours before the engine starts on its run. 

Question 475. What should be done when the locomo- 
tive leaves the engine-house and before the train is started ? 

Answer. Before leaving the engine-house the cylin^ 
der cocks should be opened, so that all the water or 
steam which is condensed in warming the cylinders 
can escape. Before the engine is started from the 
engine-house the bell should be rung and time enough 
allowed for any workmen employed about the engine 
to get out of the way. This rule must be scrupulously 



480 Catechism of the Locomotive. 

obeyed under all circumstances, and a locomotive should 
never "be started without first giving such a signal. 
Without it there is always danger that some one 
about the engine will be hurt or killed. While run- 
ning from the engine-house to the train the runner 
should observe very carefully the working of all the 
parts of his engine, and as far as possible see that they 
are in good working condition. The fireman should stay 
on the tender to handle the brake, as may be neces- 
sary, and should assist in coupling the tender to the 
first car of the train. The junction with the train, es- 
pecially when it is a passenger train, should be made 
very gently, as otherwise passengers may be injured 
by the shock. Before starting the runner should see 
himself that the engine and tender are securely coup- 
led together, and the latter to the train, that the fric- 
tional parts are property lubricated, as explained here- 
tofore, that the fire is in good condition and that the 
requisite quantity of steam has been generated. If 
the steam is too low, the blower is started, which 
stimulates the fire. 

Question 476. When the train is ready, how should 
the engine be started? 

Answer. After the signal to start is given by the 
conductor, the runner also gives a signal by either 
ringing the bell or blowing the whistle. The latter 
should, however, be used, especially at stations, as 
little as possible, on account of the risk of frightening 
horses and the shock which it produces on persons 
who are unaccustomed to hearing it, or are suffering 
from any nervous disorder. After giving the requisite 
signal, the runner places the reverse-lever so that the 
valve will work either in full gear or very near it. 



Running Locomotives. 481 

He then opens the throttle slowly and cautiously so as to 
start the train gradually. If the train is a very heavy 
one, it is best to back the engine so as just to " take 
up the slack of the train," that is, to push the cars to- 
gether so that there will be no space between them 
and thus compress the car draw-springs. When the 
cars stand in this way, those at the -front end of the 
train are started one after another, which makes the 
start easier than it would be if it were necessary to 
start them all at once. If the throttle is opened too 
rapidly, the driving-wheels are apt to slip, but with a 
very heavy train, even with the greatest care, this is 
liable to occur. If the train can not be started other- 
wise, the rails must be sanded by opening the valves in 
the sand-box. As little sand should be used as possi- 
ble, because the resistance of cars running on sanded 
rails is greater than on clean rails, and thus the train 
is more difficult to draw after it reaches the rails to 
which sand has been applied. Thus the difficulty to 
be overcome may be increased by the means employed 
to overcome it. 

While the train is slowly set in motion the fireman 
and runner must ascertain by watching whether the 
whole train moves together, and that none of the coup- 
lings are broken in starting, and also whether any 
signal is given to stop, as is sometimes necessary 
after the train has started. On leaving the station 
lie should observe whether all the signals indicate that 
the track is clear and that the switches are set right, 
and also look out for obstructions on the track. The 
train should always be run slowly and cautiously until 
it has passed all the frogs, switches and crossings of 
the station yard, and not until then and when the 
41 



482 Catechism oj the Locomotive. 

runner has seen that everything is in order should he 
run at full speed. As the engine gains in speed the 
reverse lever should be thrown back and nearer the 
centre of the quadrant or sector, so as to cut off 
" shorter." 

Question 477. After the engine is started, how can 
it be run most economically ? 

Answer. The advantage of using steam expansively 
has already been explained in Part V. ; it is more 
economical to use steam of a high pressure which is 
done by keeping the throttle-valve wide open, and 
then regulating the speed by cutting off shorter — that 
is, expanding it more. If the speed is reduced by 
partly closing the throttle-valve, the steam is wire- 
drawn and, as was shown in answer to Question 59, 
it then produces much less useful effect than it would 
if it was admitted into the cylinder at full boiler 
pressure. 

It is found, however, that in many cases if the 
steam is cut off very short the final pressure when it 
escapes is so low that it does not produce blast enough 
to stimulate the fire, and therefore the boiler will not 
make enough steam. This is more liable to occur 
with engines which have small than with those which 
have large boilers, or when the boilers are in bad con- 
dition or the fuel is of poor quality. When it does 
occur it is necessary to work steam during a longer 
portion of the stroke, so as to increase the final press- 
ure when it is exhausted and regulate the speed with 
the throttle-valve. Of course this is very wasteful, 
but it is often the best which can be done and pull the 
train. 

There is also another practical difficulty in using 



Running Locomotives. 



483 



steam of a high pressure and running with the throt- 
tle wide open and regulating the speed with the re- 
verse lever alone. The link motion, as has already 
been explained, will not be effective in cutting off at a 
point below about one-quarter of the stroke. Now it 
often happens, even when cutting off at that short 
point, with light trains on a level or slightly descend- 
ing grade, that the speed will be too great if the 
throttle is wide open and with full steam pressure in 
the boiler. When this is the case, it is absolutely 
necessary to reduce the speed either by partly closing 
the throttle, or reducing the pressure in the boiler. 
Undoubtedly if valve-gear for locomotives was so con- 
structed that steam could be cut off effectively at a 
shorter point of the stroke, it would result in increased 
economy in the use of steam. 

The runner should aim to run at as nearly uniform 
speed as possible, and in order to do so should divide the 
distance between stopping points and the time given 
for running it into as small divisions as he conven- 
iently can, so as to be able to tell as often as possible 
whether he is running too fast or too slow, and thus 
travel over the shorter spaces in corresponding pe- 
riods of time. 

Question 478. How should the boiler be fed? 

Answer. The feeding of the boiler should if possible 
be continuous, and the quantity of water pumped into 
it should be adjusted to the amount of work which the 
engine is doing. Ordinarily one pump is more than 
sufficient for feeding the boiler, so that usually only 
the one on the right side of the engine, where the 
runner stands, is used. The flow of the water is resu- 
lated by partly opening or closing the feed-cock. The 



484 Catechism of the Locomotive. 

injector is commonly used only when the engine is 
standing still, when the pumps will not feed. In feed- 
ing the boiler it must be seen that the water is neither 
too high nor too low. If it is too low there will be 
danger of overheating the crown-plates or even of an 
explosion; if it is too high, the steam space in the 
boiler is diminished unnecessarily, and will cause the 
water to rise in the form of a spray, and thus be car- 
ried into the cylinders with the steam, or the boiler 
will prime or foam, as it is called. This water, if it 
collects in the cylinder as already explained, may by 
the concussion produced by the motion of the piston 
break the cylinder. 

Question 479. What is the cause of priming in a 
boiler. 

Answer. It is often caused by the difference in tem- 
perature and pressure in the water below and the 
steam above. Thus, if we have a boiler in which the 
water is heated to a temperature due to 100 lbs. effect- 
ive pressure, or 338 degrees, and we then open the 
throttle- valve suddenly, so as to relieve the pressure 
on top of the water, there will at once be a rapid gen- 
eration of steam in the water which will rush to fill 
the space from which the steam has been drawn. This 
newly generated steam will be formed at the hottest 
part of the boiler first, that is, next to the heating 
surface. It will therefore happen that as soon as the 
pressure is relieved, bubbles of steam from all parts of 
the heating surface of the boiler will flow to the point 
at which the steam escapes. The motion of these 
bubbles will be so rapid that large quantities of water 
will be carried with them. The same thing will also 
occur if the heat of the water is increased very rapidly. 



Running Locomotives. 



485 



The water will then become hotter than the tempera- 
ture due to the pressure of the steam above it, and 
consequently there will be a rapid formation and es- 
cape of bubbles of steam from the water, which will 
thus have the same effect as they would have if the 
steam pressure was reduced. 

The amount of water carried up with the steam is 
increased if the escape of the latter is obstructed in 
any way, owing to imperfect circulation of water in 
the boiler, or by floating impurities, such as oil, on the 
surface. When this condition of things exists, the 
ebullition is, as it were, convulsive, and the water is 
thus carried up with the steam when it escapes. 
Priming is also probably due in some measure to the 
flow of steam over the surface of the water to the point 
of outflow,* carrying particles of water with it just as 
a high wind will, when blowing over the crests of the 
waves of the sea. 

When steam is drawn, as it usually is in locomo- 
tives, from the top of the dome to which the safety- 
valves are attached, the tendency to prime is very 
much increased when they are blowing off, so that 
some engineers advocate the use of two domes, from 
both of which the supply of steam is sometimes drawn, 
and in other cases the safety-valves are mounted on 
one, and the steam-pipe is placed in another dome. 
Whenever the safety-valves begin blowing off steam, 
the pressure in the boiler should be reduced as soon 
as possible, not only because when they are blowing 
off it tends to produce priming, but because the steam 
which escapes from them is wasted. The pressure 
can be most economically reduced either by increasing 

* Wilson on Steam Boilers. 

41* 



486 Catechism of the Locomotive. 

the amount of water which is fed into the boiler or by 
opening the heater cocks and allowing the steam to 
escape into the tank and thus warm the water. If 
the boiler is too full, the former method cannot be 
employed, and in heating the water in the tank the. 
runner must be careful not to get it too hot, because 
in that case neither the pumps nor the injectors will 
work satisfactorily, and the paint on the tenders is 
also liable to be blistered and destroyed by the heat. 
By feeling the tank with the hand it* can soon be dis- 
covered whether the water is too hot. If the steam 
pressure cannot be reduced in any other way, the fur- 
nace door must be partly opened. 

The use of muddy water will also sometimes cause 
a boiler to prime. It is probable that priming is 
sometimes due to the formation of foam on the surface 
of the water, and therefore all priming is often called 
foaming; whereas it is thought that often a boiler 
will prime when the water does not foam. More accu- 
rate information regarding the priming of boilers is, 
however, much needed, as many of the phenomena 
have thus far not been satisfactorily explained. The 
principal causes of priming in ordinary practice are, 
however, undoubtedly owing to defective circulation, 
t o little steam room, impure water, or too much 
water in the boiler. 

Question 480. How can it be known whether an en- 
gine is priming, and what should be done to prevent it ? 

Answer. The priming of a boiler can be known by 
the white appearance of the steam which escapes from 
the smoke-stack and the cylinder cocks. Dry steam 
always has a bluish color. When an engine primes 
or works water into the cylinders, it is usually 



Running Locomotives. 487 

indicated by a peculiar dead sound of the exhaust, 
which from this cause loses its distinctly denned and 
sharp sound. This can be observed best when the fur- 
nace door is opened. It is also indicated by the dis- 
charge from the gauge-cock, as the water which then 
escapes from the lower cocks is mixed with steam, or, 
as runners say, is not " solid/' and the steam from the 
upper cocks is not clear, but mixed with water. To use 
a phrase employed by practical men, the priming or 
foaming of the boiler may be known by the " nutter " 
of the gauge-cocks. As soon as there are any indica- 
tions of priming, foaming, or that water is working 
into the cylinders, the cylinder cocks should be opened 
at once, otherwise the cylinders, cylinder heads or 
pistons may be broken. The throttle-valve should be 
either partly or entirely closed. When the latter is 
done the foaming will in most cases cease for the time, 
so that the runner can tell how much solid water there 
is in the boiler. If he finds that the boiler has too 
much water in it, it is best to shut off the pumps, and 
in many cases the blow-off cock is opened. The lat- 
ter is, however, attended with some danger, because 
if any obstruction should get into the blow-off cock, or 
it should stick fast, so that it could not be closed, all 
the water would escape from the boiler, and with a 
heavy fire in the fire-box there would be great danger 
of overheating, and thus injuring the boiler or of 
"burning" it, as it is ordinarily termed. 

A much better method of affording relief in such 
cases is to place what is called a surface-cock in the 
back end of the fire-box, about half way between the 
upper and lower gauge-cocks. With such a cock, the 
water can be blown off from the surface instead of 



488 Catechism of the Locomotive. 

from the bottom. As foaming or priming is often 
caused by oil, or other floating impurities on the sur- 
face, they can be blown out of the boiler with this ar- 
rangement, whereas, if the water escapes from the 
bottom of the boiler, the floating impurities will 
always remain after it is blown off. A perforated 
pipe, which extends for some distance along the sur- 
face of the water inside the boiler, is sometimes at- 
tached to the surface-cock, so that the water which is 
blown off will be drawn from a number of points along 
the surface. 

If the steam is rising rapidly when foaming be- 
gins, it will be well to cool the boiler off by opening 
the furnace door part way. This means of relief 
should, however, be used as little as possible, because 
there is always danger of causing the tubes or other 
parts of the boiler to leak, by either heating or cooling 
suddenly or rapidly. If the engine primes when there 
is but little wa.ter in the boiler, and at a time when 
the steam is rising rapidly, it may sometimes be rem- 
edied by increasing the amount of feed-water, and thus 
partly cooling the water inside. The use of pure 
water, careful firing so as to keep the steam pressure 
regular, feeding the boiler so that the level of the 
water will be nearly uniform, and then starting the 
engine carefully, that is, opening the throttle-valve 
gradually, are the most effective means in practice of 
preventing a locomotive boiler from priming. 

Question 481. What is the economical effect of prim- 
ing on the consumption of fuel in locomotives f 

Answer. It cause a great waste of heat, first by the 
escape of that contained in the hot water which passes 
through the cylinders and which does no work, and 



Running Locomotives, 



489 



second, when steam is mixed with a great deal of 
water, it will not flow either to or from the cylinders 
as quickly or easily as dry steam will. Consequently 
the initial pressure on the piston, if the engine is run- 
ning even moderately fast, and is cutting off short, 
will not be so great as it would be if dry steam was 
■ used. Wet steam is also more difficult to exhaust 
from the cylinder than that which is dry, and there- 
fore the back pressure on the piston is greater when 
the boiler primes than when dry steam alone is used. 

Question 482. When running on the open road, what 
should the locomotive runner observe ? 

Answer. Either he or the fireman should constantly 
watch the track in front of them, and also observe, 
from time to time, whether the train of cars, espec- 
ially if it is a long one which he is handling, is in good 
condition. He must observe every signal scru- 
pulously, AND SHOULD NEVER PASS ONE UNTIL HE 
IS SURE THAT HE IS AUTHORIZED TO DO SO. The 

well-known maxim, " be sure you are right ; then go 
ahead," should be changed for locomotive runners to, 

DON'T GO AHEAD UNTIL YOU ARE SURE YOU ARE 
RIGHT, AND WHEN IN DOUBT ALWAYS CHOOSE THE 

side of safety. In running through curves, the 
speed of the train should always be moderated in pro- 
portion to the sharpness of the curve, and before reach- 
ing it. In running through curves, the tendency of 
the train is to continue in a straight line, and there is 
thus danger of running off the track. The higher the 
speed, of course, the greater is the resistance which is 
required to prevent the train from running in a 
straight line, and consequently the greater is the 
strain which is thrown on the flanges of the wheels 



490 Catechism of the Locomotive. 

and on the rails and axles. In running through 
curves, it is also impossible, usually, to see further 
than a short distance ahead, and therefore, if the train 
is running very fast, it cannot be stopped in time, 
should there be any obstruction or danger on the 
track. 

Question 483. What precautions should be observed in 
running over steep grades ? 

Answer. On approaching an ascending grade the 
runner should see that the fire is in good condition, 
and as much coal should be put on it as can be burned 
to advantage. He should also fill the boiler as full of 
water as he safely can, without danger of priming, and 
should heat this water as hot as possible without blow- 
ing off steam at the safety-valves. The object of this 
is to have a supply of water already heated before 
reaching the grade. If, as often happens with a heavy 
train, the boiler will not make as much steam as the 
engine consumes, if there is a large supply of hot 
water in the boiler it can be used as a reserve, should 
it be necessary to do so, without danger of injury to 
the boiler. If there was so little water in the boiler 
that it would be dangerous to allow it to get lower, 
then it would be necessary to feed cold water as rap- 
idly as the hot water escaped in the form of steam. 
It is often impossible to heat all this cold water as fast 
as it is pumped into the boiler, without reducing the 
steam pressure until there is then not sufficient power 
to pull the train. If, however, there is a supply of hot 
water in the boiler, at the critical point on the grade, 
where the engine is most liable to fail, the pump can 
be partly shut off, and thus less water will be pumped 
into the boiler, and the steam pressure be maintained 



Running Locomotives, 



491 



without danger. Undoubtedly it is better to feed lo- 
comotive boilers uniformly, if that is possible, but it 
often happens that a reserve supply of hot water in 
the boiler enables an engine to pull a train up the 
most difficult place, whereas, without such a supply, 
the locomotive would stick fast. As the capacity of 
locomotives is rated on nearly all roads by the number 
of cars they can " pull up the hill," of course whatever 
aids them at the critical point increases their capac- 
ity. It is this fact which gives engines with large 
boilers so much advantage over those with small ones. 
In running up steep grades, allowance should always 
be made for the effect of the inclination of the track 
upon the position of the water surface in the boiler, 
and also the fact that as soon as the throttle-valve is 
closed, and steam shut off, the surface of the water 
will be considerably lower than when the engine was 
working hard. On a grade of 50 feet to a mile, the 
front end of the tubes of an ordinary locomotive would 
be about If inches higher than the back end of the 
crown-sheet. If, then, on working hard up such a 
grade, it is succeeded by another of equal descent, the 
front ends of the tubes would be 1| inches lower than 
they were while coming up, so that if the back end of 
the crown-sheet was covered with If inches of water 
just before reaching the top, it would be exposed to 
the fire as soon as the engine reached the descent. 
This exposure would be dangerous, because not only 
would the water be If inches lower over the crown- 
sheet, but it would fall considerably more when the 
throtfcle-valve was closed. These considerations will 
show the danger of running the water too low while 
ascending steep grades. 



492 Catechism of the Locomotive, 

In pulling trains up steep grades, especial caution 
should be exercised to prevent any of the cars from 
breaking loose from the train, because such an acci- 
dent may cause great disaster. 

As soon as the engine reaches the top of the grade, 
the fireman should oil the main valves, because it can 
only be done when steam is shut off, as the oil will 
not run into the steam-chest when there is a pressure 
of steam in it ; and as the valves are always subjected 
to the severest wear while pulling up a steep grade, 
the valves and valve-faces are apt to become dry. As 
saturated steam to some extent prevents valves from 
cutting, it is not so important that they be lubricated 
while the engine is working with steam, but as soon 
as steam is shut off they should be oiled, otherwise 
there is danger of their being injured by their friction 
on the valve-seats. 

In running down grades, the runner has the great- 
est possible cause for using every precaution, because 
not only is the train much more difficult to control, but 
usually frequent sharp curves prevent a view of the 
track for any considerable distance ahead. He should, 
therefore, watch the track in front of him with the 
greatest vigilance, so as to be ready to give the requi- 
site signals to the brakemen to apply the brakes, or, if 
the engine and train are provided with continuous 
brakes, to apply the latter, or even reverse his engine, 
in case of danger. 

Question 484. How should an engine be run past 
those stations where the train does not stop ? 

Answer. The speed of the train should be slackened 
in passing stations, especially if a clear view of the track 
and switch signals can not be obtained at some dis= 



Running Locomotives. 493 

tance before reaching the station. There is always a 
possibility that the switches may be turned wrong, or 
that there may be some obstruction on the track at 
stations, so that some caution should be exercised in 
running past them. The proper signal, either by the 
whistle* or the bell, should be given on approaching 
stations, and also at all common road crossings. 

Question 485. What must be done on approaching a 
draw-bridge or a crossing of another railroad at the same 
level? 

Answer. In many of the States it is provided by 
law that all trains must come to a dead stop before 
crossing a draw-bridge or another railroad at the same 
level. Whether such a law exists or not, the rule 
should always be observed. After coming to a stop, 
the train should under no circumstances be started 
until the signal has been given to start the train by 
the signal-man at the bridge or crossing. A runner 
should never assume that the signal has been given, 
nor take another person's word for it, but should see 
and know it himself. In some conditions of the 
weather and with the light falling on a signal in cer- 
tain directions, it is sometimes difficult to determine 
its color or form. If there is any doubt about it, the 
testimony of another person should always be sought. 
There is good reason for believing that color-blind- 
ness, that is, an incapacity for distinguishing one 
color from another, is a much more common infirmity 
than is usually supposed. It is certain, too, that 
people who ordinarily distinguish colors very accu- 
rately are subject to color-blindness in certain condi- 



* The methods of giving signals vary so much on different roads that 
no general direction that will suit all cases can he given. 

42 



494 Catechism of the Locomotive. 

tions of health, and that it is sometimes the result of 
overwork or great weariness ; and a case is recorded 
of a person who was always color-blind after a de- 
bauch. There are, therefore, good reasons why a lo- 
comotive runner should not always place too implicit 
confidence in what he " sees with his own eyes," but 
if he has any doubt, he should take the " benefit of 
the doubt," which should always lead him to take the 
side of safety. 

Question 486. Hoiv should the engine and train be 
managed in running into a station ? 

Answer. First of all when running into a station 
when the train stops, the speed must be checked so 
that the train will not enter with very great momen- 
tum. Therefore, at a distance varying from one to 
three-quarters of a mile, according to the nature of 
the grades and track, the steam should be shut off, so 
that the speed will be reduced so much that the train 
under any circumstances will be under full control. 
It is always better to enter a station at too low a speed 
than to run in too fast, because if it is necessary, more 
steam can always be admitted to the cylinders to in- 
crease the speed before coming to a stop ; whereas it 
is not so easy to stop the train if it is running too 
fast, and it becomes necessary to check it before en- 
tering the station. This will sometimes be necessary, 
because it may readily happen through negligence or 
accident at stations that in switching cars one or 
more may be left standing wholly or partly on the 
track, which the arriving train must run over, in 
which case a collision with its terrible consequences 
may be unavoidable. 

When a train is equipped with continuous brakes, 



Running Locomotives. 495 

the control which they usually give to a locomotive 
runner over the train is so great that he is apt to ap- 
proach stations, crossings or draw-bridges at a high 
rate of speed, and rely on such brakes to stop the 
train. This practice is always attended with great 
danger, because if it was found, on getting near to the 
station, crossing or draw-bridge, that the track was 
not clear, and that it was obstructed by a car or train, 
or the draw was open, if the runner should attempt 
to apply the brakes and from some cause they should 
fail to work, as sometimes occurs, then a collision or 
other disaster would be inevitable, because it would 
be impossible to stop the train with the ordinary hand 
brakes. For this reason a locomotive runner should 
always approach such places cautiously and with his 
train under sufficient control, so that if he finds there 
is danger ahead he can stop the train with the ordi- 
nary means, or at the worst by reversing the engine. 
Continuous brakes should always, excepting in cases 
of imminent danger, be applied gradually, so as not 
to check the cars with a jerk or too suddenly. The 
practice of opening the cock which admits air to 
atmospheric brakes suddenly, and then turning it 
back again as quickly, is almost sure to produce disa- 
greeable and dangerous shocks to the cars. The cock 
should be opened gradually, so as to check the cars 
slowly at first. 

Question 487. What must he attended to when run- 
ning a locomotive at night ? 

Answer. As soon as it begins to grow dark, the 
head-light must be lighted and properly trimmed, and 
the proper lamp signals placed in front of the engine, 
if the rules of the road require the display of such 



496 Catechism of the Locomotive, 

signals. A lamp should always be placed in the cab, 
so as to throw its light on the steam-gauge, but not 
into the runner's face, because he is unable to see dis- 
tant signals so well if his eyes are exposed to the 
glare of a light near him. 

At night, as objects which are passed can not be 
seen distinctly, it is more difficult to tell the speed at 
which an engine is running than it is in the day time. 
A runner should therefore consult his watch fre- 
quently, and by counting the revolutions of the 
wheels, which he can do by the sound of the pump 
valve or other part of the machinery, he can tell from 
the rule given in the answer to Question 438 the 
speed at which the locomotive is running. From this 
rule a table can easily be constructed for an engine 
with any size of driving-wheels, showing the speed 
for any given number of revolutions per minute. It 
will be a good exercise for a young locomotive runner to 
construct such a table, which will be found very con- 
venient for reference if placed in a conspicuous place 
in the cab. 

Question 488. What must be attended to in very cold 
weather ? 

Answer. Great care must be exercised to prevent 
the water in the pumps, pipes and in the tender from 
freezing. If it does it will be almost certain to break 
the pump or burst the pipes. To avoid this the 
heater cocks must be opened so as to keep the water 
in the tender warm. In excessively cold weather the 
engine should be run with greater caution th#n at 
other times, as iron is then more brittle, and also 
more liable to break, owing to the frozen condition 
and consequent solidity of the track. 



Running Locomotives. 497 

Question 489. In running a locomotive in severe 
snow or rain-storms, what should be observed f 

Answer. Whenever it snows the pilot or cow catcher 
should be covered with boards, or, better still, with 
sheet iron, so as to act like a snow plow. Brooms 
made of steel wire should be placed in front of the 
front wheels of the engine, so as to sweep the snow 
from the rails. The front damper on the ash-pan 
should be kept closed so as to exclude the snow from 
the ash-pan, which would soon fill it up, and in this 
way obstruct the draft. If the fall of snow is very 
heavy or it blows into drifts, the train must of neces- 
sity run very slowly, and even if a part of the track 
is clear of snow, it is unsafe to run fast on it, as there 
would be danger of throwing the engine off the rails 
if it should run into a heavy drift at a high speed. 

In severe rain storms bridges, culverts and such 
portions of the track as are liable to be washed away 
should be approached cautiously, especially at night. 
In both snow and rain-storms, and also in fogs, great 
caution is required, owing to the difficulty of seeing 
signals. 

Question 490. What is meant by a reserve engine or 
u helper?" 

Answer. A reserve engine is a locomotive which is 
not employed in hauling a regular train, but is kept 
as a " reserve " to go to the help of an engine which 
may be compelled to stop on account of an accident of 
any kind, or to assist engines in moving trains up 
heavy grades, or is used in clearing away a wrecked 
train, rebuilding bridges or other structures. 

Question 491. What must be observed in running a 
reserve engine. 
42* 



498 Catechism of the Locomotive, 

Answer. As no special arrangements are usually 
made in preparing time-tables* for the running of re- 
serve, or as they are usually called by railroad men, 
"wild" engines, it may very probably happen that it 
will be called upon to assist other engines when the 
road is not clear, and therefore its runner must con- 
stantly be on the look-out for signals to stop, which 
are often given suddenly. He must switch off with 
special caution in order to be sure to keep out of the 
way of regular trains running in the opposite direc- 
tion on the same track. When he reaches the train 
or place where the assistance of the reserve engine is 
needed, he must approach it slowly and carefully, in 
order to avoid a violent shock. On the return from 
the assisted train, he incurs the same danger, and 
must pay close attention to any signal to stop made to 
him by any opposite train on the same track, and also 
on his part warn such trains by the proper signals. 

When a train is run with two engines, both in front 
of it, the forward one always takes the management 
of the train. The runner of the hind engine must be 
guided by the signals of the runner of the forward en- 
gine. In starting, the forward engine must be set in 
motion first and then the one behind it. In stopping, 
the steam must be shut off first in the hind engine. 
Likewise in decreasing the speed during the trip, the 
hind engine must first regulate the flow of steam. If 
these precautions are not observed the forward engine 
may easily be thrown from the track by the faster mo- 
tion of the hind one. 

When a train is assisted by a " helper " placed be- 

* A time-table is a table which gives the time when each train shall 
arrive at the stations it passes, the stations at which it shall stop, and 
all the regulations by which it shall be run. 



Running Locomotives. 499 

hind the train, and therefore pushing it, the forward 
engine must likewise be set in motion first, and steam 
should be let on in the hind engine only after a signal 
has been given by the runner of the head engine. 
During the run both engines must move with the 
same speed.* 

Question 492. How should switching engines be 
managed f 

Answer. In pushing and switching the freight cars 
in the station-yard, they should be moved carefully 
and severe shocks must be avoided, as the cars, the 
goods with which they are loaded and the persons em- 
ployed about them may be injured by violent concus- 
sions. The runner must also follow the instructions 
of his superior strictly and cheerfully, and should exam- 
ine patiently and observe with discretion the sugges- 
tions of employes who are not his superiors. 

In this service it is also of special importance that 
the runner give a distinct signal with the whistle or bell 
before every movement of his engine, in order to warn 
in time those who at such times often stand on the 
track in the way of the engine or cars, or the persons 
engaged in loading, cleaning or repairing the cars, 
and thus give them time to get out of the way.f 

Question 493. In firing a locomotive, what are the 
most, important ends to be attained? 

Answer. That which is of first and chief impor- 
tance is to make steam enough, so that the locomotive 
can pull its train and "make time"t', second, it must 



*Katechismus der Einrichtung und Betriebes der Locomtive, by 
Georg Kosak. 

t Georg Kosak. 

$ The term make time means to run at the speed indicated on the time- 
table. 



500 Catechism of the Locomotive. 

make the requisite quantity of steam with the least 
consumption of coal, and third, with the least produc- 
tion of smoke, although the latter, independent of the 
economy of combustion, is considered of importance 
only with passenger trains. What is frequently lost 
sight of in considering this subject is the fact that 
with all locomotives it often happens that it is a mat- 
ter of extreme difficulty to make enough steam to do 
the work required of the engines. When a freight 
train is struggling up a grade with a heavy train, or 
an express engine is obliged to make time under sim- 
ilar conditions, it often depends entirely upon the 
quantity of steam which can be generated in the 
boiler in a given time whether the engine will fail or 
not. In firing, therefore, the most important end to 
be aimed at is often simply to produce the largest 
amount of steam possible in a given time, even at the 
sacrifice of economy or by producing any quantity of 
smoke. Any means of economizing fuel or of smoke 
prevention, which reduces the steam-producing capac- 
ity of boilers, is therefore quite sure to be abandoned 
in time. 

Question 494. How can a boiler be made to produce 
the largest quantity of steam in a given time ? 

Answer. By burning the greatest quantity of fuel 
possible on the grate in that time. This can be done 
by keeping the grates free from clinkers and the ash- 
pan from ashes, and then distributing the coal evenly 
over the grates in a layer six to twelve inches thick. 
The thickness of the layer which will give the best 
results will, however, vary with the quality of the 
fuel, and must be determined by experience. If the 
layer is too thick, not enough air will pass through it 



Running Locomotives. 501 

to burn the coal. If it is too thin, then so much air 
will pass through that the temperature in the tire will 
be reduced. The rapidity of combustion will also be 
promoted by breaking up the coal into lumps the size 
of a man's fist or smaller. If fine coal is used it 
should be wet, otherwise it will be carried into the 
flues by the blast before it is burned or caked or even 
reaches the grate. Experience will indicate the 
amount of air which can advantageously be admitted 
above the fire in order to secure the maximum pro- 
duction of steam. The best size of the exhaust noz- 
zles and the position of the petticoat pipe must also 
be determined by experience. It will usually be 
found, however, that if enough air is admitted above 
the fire to prevent smoke, it will reduce the maximum 
amount of steam which can be generated in a given 
time. The fire should also be fed regularly and with 
comparatively small quantities of fuel at a time, al- 
though if the feeding is too frequent there is more 
loss from the cooling effect which results from the 
frequent opening of the furnace door than is gained 
from the regularity of the firing. In this, too, a fire- 
man must consult experience to guide him. 

Question 495. How can a locomotive be fired with 
the least consumption of coal 9 

Answer. Two systems of firing are practiced in this 
country, one known as the " banking system " and 
the other the " spreading system." When the bank- 
ing system is employed, the coal is piled up at the 
back part of the fire-box, as shown in fig. 218, and 
slopes down towards the front of the grate, where the 
layer of coal is comparatively thin and in an active 
state of incandescence. The heap of coal behind is 



502 Catechism of the Locomotive, 

gradually coked by the heat in the fire-box and the 
gases are thus expelled. Openings in the furnace 
door admit air which mingles with the escaping gases, 
which then pass over the bright fire in front, and are 
thus supposed to be consumed. When the "bank" 
of coal behind becomes thoroughly coked, it is pushed 
forward on the bright fire and fresh coal is again put 
on behind to be coked. This system of firing is prac- 
ticed on some roads with good results, but it is doubt- 
ful whether it could be used successfully with coal 
which cakes and clinkers badly. 

The spreading system is most commonly employed 
in the Western States, where the coal contains a 
great deal of clinker. When this is practiced, the 
coal is spread evenly over the whole of the grate in a 
thin layer, and its success and economy depend upon 
the regularity and evenness with which this layer of 
coal is maintained and the fire fed. The thickness of 
the coal must be adapted to the working of the engine. 
When it is working lightly, the layer of coal should 
be thin, but when the engine is pulling hard the layer 
of coal must be thicker, otherwise the violent 
blast may lift the coal off the grates. The suc- 
cess of this system, as was explained in answer 
to Question 388, depends upon the manner in 
which the thickness of the fire is regulated, on the 
admission of the proper amount of air above the fire, 
and on the frequency with which the fire is supplied 
with coal. When this system of firing is employed not 
more than two shovels-full of coal should be put into 
the fire-box at once, and if the engine is not working 
hard, one or even less will be sufficient. The firemen 
must, however, determine by experience the thickness 



Running Locomotives, 503 

of fire, amount of air which should be admitted and the 
frequency of firing which will give the best results in 
practice. Doubtless these will vary with different kinds 
of fuel and the construction of engines. Usually the 
greatest obstacle in the way of producing good results 
is the fact that firemen would rather "take things 
easy" than exercise that diligence and observation 
which will alone insure success in any occupation. 
Question 496. How can smoke be most effectually 



Answer. The means of preventing smoke were very 
fully explained in answer to Questions 379 and 388. 
It may be said briefly that this can be done only by 
properly regulating the supply of air which is admit- 
ted to the fire. The means of doing this have already 
been explained. 

Question" 497. What method of firing is employed 
when anthracite coal is used f 

Answer. The spreading system alone is then used. 

Question 498. How may the rules which firemen 
should observe when bituminous coal is used be briefly 
stated f 

Answer. 1. Keep the grate, ash-pan and tubes 
clean. 2. Break the coal into small lumps. 3. Fire 
often and in small quantities. 4. Keep the furnace 
door open as little as possible. 5. Consult the steam 
gauge frequently, and maintain a uniform steam press- 
ure, and if necessary to reduce the pressure do it by 
closing the ash-pan dampers rather than by opening 
the furnace door. 

Question 499. On arriving at a station where a 
train stops longer than a few minutes, what should the 
locomotive runner and fireman attend to ? 



504 Catechism of the Locomotive. 

Answer. The runner should examine thoroughly all 
the parts of his engine, as has been heretofore ex- 
plained. He should especially examine all the journals 
and wearing surfaces to see whether they are hot. 
This he can discover by feeling them. If any of them 
have become very much heated, they must be cooled 
by throwing cold water on them, and then thoroughly 
oiled. In oiling a hot journal mineral oil should 
never be used, as it is easily evaporated by the heat 
and then takes fire. Animal oil should therefore al- 
ways be used on a hot bearing. The working parts 
should be thoroughly lubricated, as already explained. 

The fireman should examine the tank and see 
whether it is necessary to take in a fresh supply of 
water. He should then examine the grates and ash- 
pan, and clean the cinders and clinkers from the for- 
mer, and the ashes from the latter. Neglecting to 
clean the ash-pan may result in melting and destroy- 
ing the grate-bars, and by obstructing the admission 
of air to the grates the ashes prevent the combustion 
from being as complete as it would be otherwise. 
With some kinds of fuel it is necessary to clean the 
tubes frequently, which must often be done at stations 
where the train stops. 

During the stop, as thorough an inspection of the 
engine should be made by the runner and fireman as 
the time will permit ; but any unnecessary waste of 
time must be avoided, and the firing should be so man- 
aged that nothing need be done about it during the halt 
at the station. On starting again the same precau- 
tions should be exercised as on making the first start. 

Question 500. After reaching the end of its run, how 
should an engine be cleaned and repaired ? 



Running Locomotives. 505 

Answer. Before leaching the last station the firing 
.should be so managed that there will be as little fire 
as possible remaining in the fire-box at the end of the 
run. After the arrival the engine should be run over 
a pit which is usually provided for the purpose, and 
the fire should be raked out of the fire-box by drop- 
ping the drop-door if there is one to the grate, or 
turning the grate-bars edgewise, or withdrawing one 
or more of them if it is necessary to do so. In this 
way the fire will fall into the ash-pan, from which it 
can easily be raked. After all the fire is withdrawn 
the dampers and furnace door should be closed so as 
not to allow the cold air to cool the fire-box and tubes 
too rapidly. 

In order to keep the boiler clean, that is as free as 
possible from sand, sediment or incrustation, it is neces- 
sary to blow it out frequently if the water which is 
used contains much solid or incrustating matter. 
With " bad water " the boiler should be blown out as 
often as possible. On some roads this is done after 
each trip. In blowing a boiler out, the blow-off cocks 
must be left open, and after all the water has escaped 
the engine should be left to stand until it is cooled off. 
If there is any considerable accumulation of mud or 
sediment the hand-holes at the bottom of the fire-box 
and the cover to the mud-drum should be taken off, 
and as much of the mud removed as can be scraped out 
through those apertures. A hose pipe attached to the 
hose of a force pump should then be inserted through 
these same openings, and a strong stream of water 
forced into the boiler. By this means much of the 
loose mud and scale will be washed out. The oftener 
this is repeated of course the cleaner can a boiler be 
43 



506 Catechism of the Locomotive. 

kept. If a large amount of incrustation or mud has 
accumulated about the tubes, some or all of them 
must be taken out, so as to be able to remove the dirt. 

After an engine is blown out, under no circum- 
stances excepting absolute necessity should it be filled 
with cold water until it is entirely cooled off. It 
should be remembered that any sudden change of tem- 
perature in a boiler subjects it to very great strains 
and incurs the danger of cracking the fire-box plates, 
or causing the tubes to leak. 

The tender should also be cleaned of the mud which 
settles in it from time to time, but it is not necessary 
to do this as often as it is to clean the boiler. All the 
plates and flues should have the soot which sticks to 
them thoroughly cleaned off. 

Although the cleaning of the boiler and the grates 
is usually committed to a special set of men, yet the 
locomotive runner should examine them personally to 
see that it is properly done. He should pay attention to 
the condition of the grate, and see whether it is level and 
smooth. As soon as one or more of the bars are bent 
crooked, they usually burn out. If one of the bars is 
burnt out the fire falls through the hole that it leaves 
into the ash-pan, and then the fire under the grate 
will heat it red hot, and finally may melt every bar. 
Every grate-bar which is only a little damaged or bent 
must therefore be removed as quickly as possible and 
replaced with a new one. 

As soon as the engine is run into the engine-house, 
all superfluous grease which has escaped from the 
wearing surfaces and the dust or mud which adheres 
to the engine should be wiped off with cotton waste 01 
•:ags. This is usually done by men employed for the 



Running Locomotives. 507 

purpose. While they are doing this, they should ex- 
amine every part thoroughly and observe whether it 
is in good condition, and if any defects are found they 
should be reported to the proper person whose busi- 
ness it is to have them repaired. As the faithfulness 
and skill of a fireman are often estimated by the good 
or bad condition of his engine, he should, if for no 
other reason, take pains to keep it clean and every- 
thing in as good condition as, possible. 

If the engine is taken to pieces in order to be thor- 
oughly repaired, the runner, if he does not help to do 
this, should watch carefully the taking it apart and 
the putting it together again, as in this way he can 
become thoroughly familiar with the construction of 
the machine he runs, 

Question 501 What precaution must be taken to pre- 
vent the water in a locomotive from freezing, if it is laid 
up? 

Answer. In very cold weather, if engines are laid 
up for any considerable time, no water must be left in 
the tender, boiler or any of the pipes. If, however, 
the engine must be soon used, and it is impracticable 
to let the water out of the boiler and tender, then, if 
exposed to the cold, a light fire must be kept in the 
boiler sufficient to make steam enough to warm the 
water in the tender. The water should, however, be 
drawn out of the pumps and the feed and supply 
pipes, This can be done by opening the pet-cocks, 
and closing the tender valves and uncoupling the hose, 
which will allow the water in the supply pipes to run 
out. By running the engine a few revolutions the 
pumps will then be emptied. The pipes and the 
pumps can also be prevented from freezing without 



508 Catechisyn of the Locomotive. 

uncoupling the hose if the tender valves are closed and 
the pet-cocks opened, and steam is then admitted into 
the supply pipes by the heater-cocks. This forcts 
part of the water which is in the pumps out of the pet- 
cocks and warms the rest. This, however, requires 
constant watchfulness to prevent freezing, and in ex- 
cessively cold weather, if the engine must lay up for 
any considerable time, it is always best to empty the 
pumps and pipes. 



PART XXVIII. 
ACCIDENTS TO LOCOMOTIVES. 

Question 502. What are the most serious accidents 
which may happen in running a locomotive ? 
Answer. The most serious accidents are : 

1. Collision of two trains approaching each other. 

2. Collision of a moving with a standing -train. 

3. Collision of trains at the crossing of two rail- 
roads. 

4. Eunning a train into the opening left by an open 
draw-bridge. 

5. Escape of an engine without any one on it. 

6. Running off the track. 

7. Explosion of the boiler. 

8. Bursting or rather collapse of a flue. 

9. Blowing out of a bolt, stud or rivet from the 
boiler. 

10. Failure of the feed-pumps, injector or check- 
valve. 

11. Breaking or bursting of a cylinder, cylinder- 
head, steam-chest, or steam-pipe. 

12. Breaking or getting loose of the piston or cross- 
head or bending of the piston-rod. 

13. Breaking or bending of a connecting-rod oi 
crank-pin. 

14. Breaking of a tire, wheel or axle. 

15. Breaking of a spring, spring-hanger or equalizer. 

43* 



510 Catechism of the Locomotive. 

16. Breaking of a frame. 

17. Breaking or getting loose of a part of the valve- 
gear. 

18. Failure of the throttle-valve. 

19. Breaking of a coupling. 

Question 503. What should be done to prevent a col- 
lision when two trains are approaching each other ? 

Answer, The obvious thing to do is to stop the trains 
as soon as possible. This is done by applying the brakes 
at once with all their power, and then reversing the 
engine, although it is best not to do the latter until the 
train is some wn at checked, as there is always danger 
cf bursting the cylinder or breaking the cylinder-heads, 
piston or connections if an engine is reversed sud- 
denly at a high speed. Of course the higher the speed, 
the greater is the danger of injury from this cause, 
and therefore it is best, if there is time, first to check 
the speed of the train before reversing the engine. 
When the engine is reversed, the sand-valves should 
be opened so as to increase the adhesion of the wheels, 
so that when their motion is reversed they may check 
the speed of the train as soon as possible. On per- 
ceiving danger ahead the order of procedure should be 
as follows : 

1. Shut the throttle-valve. 

2. If the train is equipped with hand brakes alone, 
blow the danger signal for their application, or if the 
train has a continuous brake, apply it with its full 
force. 

3. Reverse the engine and open the throttle and the 
sand valves. 

4. If a collision is inevitable, shut the throttle- valve 
before the engines meet, because if it is left open, after 



Accidents to Locomotives. 511 

the collision and when the speed of the train is checked, 
the engine, if not disabled, will by its own power crush 
through the wreck and thus do additional damage. 

Question 504. What should be done if a standing 
train should see another train approach it and there 
should be danger of a collision f 

Answer. The locomotive runner of the standing 
train should start his engine in the same direction as 
the approaching train is running, as quickly as possi- 
ble, because the shock of the collision will be very 
much lessened if both trains are moving in the same 
direction compared with what it would be if one was 
standing still. 

Question 505. What should be done to avoid a col- 
lision at a railroad crossing ? 

Answer. As was explained in answer to Question 
485, trains should always come to a dead stop before 
crossing another railroad on the same level. If, how- 
ever, through any means danger of such a collision 
should be incurred, then evidently the one train 
should be stopped and the other moved out of the 
way as soon as possible. 

Question 506. How can an accident by running into 
the opening at a draw-bridge be avoided ? 

Answer. First by always coming to a dead stop 
before reaching it, and second by not starting again 
until it is absolutely certain that the draw is closed. 
Of course if a locomotive runner of an approaching 
train finds a draw open, the only thing he can do is 
to stop as soon as possible. 

Question 507. What measures should be taken to 
prevent locomotives from escaping without a responsible 
person on them f 



512 Catechism of the Locomotive. 

Answer. In the first place when a locomotive is left 
standing the throttle-valve should always be closed and 
fastened, the cylinder cocks should also be opened so 
that if any steam leaks into the cylinders it will not 
accumulate there, but will escape, and the reverse 
lever should be placed in the centre of the sector, so 
that if by any accident the throttle should be opened 
the engine will not start. 

Question 508. If a locomotive should escape, what 
should be done, and how may it be captured? 

Answer. The first thing to be done is to telegraph 
to the stations towards which the escaped engine is 
running, either to keep the track clear, or, if there is 
a train approaching, to open a switch and thus let the 
engine run off the track. An escaped engine may be 
captured by a swifter engine following it, but this is 
always attended with great danger, as the first engine 
may leave the track or become wrecked. A safer plan is 
to telegraph ahead of the escaped engine and have 
an engine placed in a position where the track can be 
seen for a long distance in the direction in which the 
runaway is expected. As soon as the latter comes in 
sight, the waiting engine should start in the same di- 
rection, so that when they get near to each other they 
will both be running in the same direction and at 
nearly the same speed. By regulating the speed of 
the front engine, the following one may be allowed to 
come up to it quite gently, and then a man can easily 
climb from the one engine to the other, and thus both 
be stopped. 

Question 509. What should be done in case an en- 
gine gets off the track f 

Answer. The first thing to do is to close the throt- 



Accidents to Locomotives, 513 

tie-valve and " signal for brakes,"* or apply the con- 
tinuous brakes if the train is equipped with them, 
and then reverse the engine. If its position after it 
stops is much inclined, it is generally necessary to 
draw the fire to prevent injury to the heating-surface, 
a part of which is then usually exposed to the steam, 
and therefore not covered with water. 

Question 510. How is a locomotive replaced on the 
track in case it gets off ? 

Answer. It is impossible to give any directions for 
replacing locomotives on the track which will meet 
the great variety of circumstances which occur in 
practice. If the engine has not run far from the rails, it 
can usually be run on again by placing blocks of wood 
under the wheels and thus running them up to their 
proper position, but if the engine falls on its side or 
runs down an embankment, it is usually necessary to 
send for the appliances which are now provided on 
nearly all roads for removing wrecks and replacing 
engines on the track. These appliances are generally 
stored in what is called a wrecking or tool car, which 
is placed at a convenient point on the road, from 
which it can be sent to any place where its services 
are likely to be needed. Such cars are generally pro- 
vided with ropes, jack-screws, chains, crowbars, levers, 
etc., to be used in such cases, and generally a special 
set of men is sent with the wrecking car to direct and 
assist in replacing engines and cars on tho track. It 
would lead us too far to describe all the methods of 
doing this employed under various circumstances ; and 
as such work seldom forms part of the duties of a lo- 



* This expression means, among railroad men, to signal to brakemen 
by blowing the whistle to have them apply the brakes. 



514 Catechism of the Locomotive. 

comotive runner, a complete description would be out 
of place here, 

Question 511. After an accident which disables the 
engine, what is the first thing to do f 

Answer. The first thing to do is always to "protect 
the train ; " that is, to send out signal men in each di- 
rection to stop approaching trains ; otherwise they 
might run into the wrecked train, and thus cause a 
double accident. 

Question 512. What is the chief cause of boiler ex- 
plosions ? 

Answer. The cause of all boiler explosions, as hap- 
pily expressed by a prominent American engineer,* 

is THAT THE PRESSURE INSIDE THE BOILER IS 
GREATER THAN THE STRENGTH OF THE MATERIAL 

outside to resist tkat pressure. This may occur 
\n two ways : first, and most frequently with locomo- 
tives, from insufficient strength of the boiler to bear 
the ordinary working pressure ; and second, from the 
gradual increase of heat and pressure until the latter 
is greater than the boiler was calculated to bear. 

Insufficient strength may be due : 1, to defects of 
the original design, owing to the ignorance of the 
strains to which the material of the boiler will be ex- 
posed, and its power of resistance ; 2, to defective 
workmanship and material, which can usually be dis- 
covered by careful inspection ; 3, to the reduction of 
the original strength of the boiler by ordinary wear 
and tear or neglect, which can also usually be discov- 
ered by careful inspection. 

The first two causes have been fully discussed in 



* See Fifth Annual Report of the American Master Mechanics' Asso- 
ciation, page 196. 



Accidents to Locomotives, 515 

the part relating to boiler construction, and the last 
under the head of inspection of locomotives. 

Over-pressure is nearly always due to some defect 
of the safety-valve, or to the fact that it is overloaded. 
This latter often occurs when safety-valves are set by 
a defective steam gauge, which indicates too little 
pressure. Over-pressure may also occur by letting an 
engine stand alone with a large fire in its fire-box and 
possibly with the blower turned on. 

A boiler may, by suddenly opening the throttle- 
valve, undoubtedly be subjected to very severe strain 
that may possibly be sufficient to cause its destruction, 
even though it had sufficient strength to bear the or- 
dinary pressure at which the safety-valve blows off. 
Suddenly opening or closing the throttle-valve may 
produce a violent rush of steam and water against the 
part of the boiler whence the steam is drawn. The 
percussion of the water and steam in such cases has 
been known to shake the whole boiler, and to lift the 
safety-valve momentarily right off its seat.* The 
weakest parts of a locomotive are the two sides where 
the barrel joins the outside fire-box. Many boilers, 
especially those with a high wagon-top, have flat 
spaces at this point, which it is impossible to stay 
properly. It is at this point, too, that the expansion 
and contraction of the tubes and the outside shell 
exprt their greatest strains, and it will therefore be 
found, generally, that the seams at this point begin 
to leak before any others, and for these reasons it is 
believed that all the seams which join the outside 
shell of the fire-box to the barrel should be double- 
riveted. 



* Wilson on Boiler Construction. 



516 Catechism of the Locomotive, 

The practice of ascribing steam-boiler explosions to 
obscure causes has been productive of much mischief, 
as it engenders a carelessness on the part of those 
having charge of them, who have been led to believe 
that no amount of care will avail against the myste- 
rious agents at work within the boiler. Explosions 
are also, in the absence of other convenient reasons, 
very generally attributed to shortness of water. This 
is often nothing more than a convenient method of 
shifting the responsibility from the builder or owner 
of the locomotive to the runner or fireman, who, if 
not killed by the explosion, in many cases might just 
as well be, so far as his ability to defend himself is 
concerned.* 

Question 513. What should a locomotive runner and 
fireman do to avoid and prevent explosions f 

Answer. 1. The height of the water in the boiler 
should always be maintained so as to cover the heat- 
ing surfaces. 2. The boiler should be kept as clean, 
that is, as free from scale, mud and other impurities, 
as possible. 3. It should never be subjected to strains 
from sudden heating or cooling. 4. The steam-gauge 
and safety-valves should be examined and tested fre- 
quently, to be sure they are in order; and 5, they 
should examine every part of the boiler which is ac- 
cessible, but especially the stay-bolts, to see that 
there is no fracture of any part or any injurious cor- 
rosion or other dangerous defect. 

Question 514. What should be done in case of the 
bursting or collapse of a tube ? 

Answer. As soon as possible after it occurs, the 
runner must stop the train, and close first the end of 



* Wilson on Boiler Construction. 



Accidents to Locomotives, 517 

the flue in the fire-box, and then that in the smoke- 
box, by driving in iron plugs, which are usually pro- 
vided for the purpose. These plugs are attached to 
the end of a bar, with which they are inserted into 
the tubes. If the escape of water and steam from the 
tube is so great as to make it difficult to see the end 
of the tube, the steam may sometimes be drawn up 
the chimney by starting the blower. If, however, 
the escape is so great as to make it impossible to in- 
sert the plug, then the steam pressure must be re- 
duced by running with both pumps on, or by starting 
the injector ; or it may be necessary to draw the fire 
and cool off the engine. When a flue collapses, the 
front end of which is behind the steam or petticoat 
pipes, it is usually necessary to cool off the engine 
before a plug can be inserted, especially if any consid- 
erable amount of water and steam escape from it. 
While driving in the plug, the runner and fireman 
should always keep themselves in such positions that 
the plug can not hit them in case it is blown out by 
the steam. If the engine is not supplied with iron 
flue-plugs, a wooden plug can be cut of the proper 
size and driven in. This can be attached to the bar 
referred to and inserted ; but if no such bar is carried 
with the engine, the wooden plug can be made on the 
end of a long pole and then cut nearly off. It is then 
inserted into the flue and driven in and broken off. 
It will be found that such plugs will burn off even 
with the end of the flue, but will not burn entirely 
out. 

Question 515. What should be done in case a bolt, 
stud or rivet blows out of the boiler and thus allows the 
steam or hot water to escape ? 
44 



518 Catechism of the Locomotive. 

Answer. If it is accessible, cut a plug on the end of 
a long pole and drive it in in the same way as described 
above. This will avoid the necessity of cooling off 
the engine ; but in some cases it will be found that a 
plug can not be inserted or driven in without draw- 
ing the fire and cooling off the boiler. 

Question 516. In case it is found necessary to draw 
the fire and cool off the boiler, and if so much water 
has escaped as to uncover the crown plate, what must be 
done ? 

Answer. If the leak has been stopped or the fault 
remedied, one of the safety-valves should be taken off 
and water poured into the boiler with pails or buckets 
through the opening left by the removal of the safety- 
valve until the crown sheet is covered. The fire may 
then be kindled again and the engine complete its 
journey. When bituminous coal is used for fuel, the 
necessity for drawing the fire in case of accident may 
often be avoided by completely covering or "bank- 
ing" the fire with fine coal which has been wet, and 
closing the dampers and opening the furnace door. 
In this way the fire may be smothered and the boiler 
cooled without putting the fire out, so that after the 
defect is remedied it will not be necessary to rekindle 
it. 

Question 517. What must be done in case of the 
failure of one or both of the feed pumps or of the in- 
jector or check-valve ? 

Answer. If one of the pumps fails the other one 
may be used, but the defect or obstruction to the first 
should be remedied as soon as possible, because the 
second may also fail. It will then be necessary to de- 
pend upon the injector alone, if there is one, for feed- 



Accidents to Locomotives. 519 

ing the boiler. Only after all the appliances for 
feeding the boiler have failed and the water is so low 
as to be in danger of exposing the crown sheet, should 
the fire be drawn or banked, and the runner should 
then at once give the proper signals for warning and 
the protection of his train, and if he is unable to repair 
the pumps or injector, he must send for aid to the 
nearest accessible point. 

Question 518. In case a pump fails, how should it 
be examined in order to discover the defect ? 

Answer. As explained in the answer to Question 458, 
the working of a pump is usually indicated by the 
stream which escapes from the pet-cock. If, when 
this is opened, steam and water escape, it is an indi- 
cation that the check-valve is not working properly. 
When this occurs hot water will escape if the pet- 
cock is opened when the engine is standing still, but 
the pump may still feed the boiler if the upper or 
pressure-valve works properly. When the check-valve 
does not work as it should, it is also indicated by the 
heating of the feed-pipe, owing to the escape of hot 
water from the boiler through the check-valve when 
the pet-cock is opened. If, when the plunger is 
drawn out of the pump, air is sucked in through the 
open pet-cock, then the upper or pressure-valve of the 
pump does not work, but the working of the pump 
may still be secured by the working of the check- 
valve ; but if the pump, air-chamber and feed-pipe 
then get filled with air, the plunger may compress 
this air at each stroke, and as it can then follow the 
plunger during its outward stroke, the latter will not 
suck water, but will simply compress the air during 
the inward stroke, which will then expand during the 



520 Catechism of the Locomotive. 

outward stroke. This will be indicated by the escape 
of air from the pet-cock when the plunger is moving in- 
ward, and the suction of air when the plunger is mov- 
ing outward. This can be known by holding the hand 
in front of the pet-cock. Usually, however, the air is 
mixed with water so that the stream which escapes 
from the pet-cock is broken or irregular. If air es- 
capes from the pet-cock during the inward stroke of 
the plunger, but none is sucked in during the outward 
stroke, it shows that there is a leak somewhere in the 
pump or pipes, and that it is pumping air instead of 
water. The leak may be in the stuffing-box of the 
plunger, the joints of the pump or pipes, in the hose 
or their connections with the supply-pipe or tender. 
If neither air nor water escapes from the pet-cock 
during the inward stroke of the pump plunger, or, if 
the stream of water at that time is weak, then it in- 
dicates that the suction or lower valve of the pump is 
not working properly. The same thing will occur if 
the pipe, pump or tender-valve is obstructed. If there 
is a cock, as there always should be, just above the suc- 
tion-valve, it will aid us very much to discover the 
fault when the pump will not work. If, when this 
cock is opened, cold water escapes from it, the fault 
is in the suction-valve ; if hot water, then it is the 
pressure and check-valves which are leaky, obstructed 
or broken, and consequently the hot water from the 
boiler leaks back into the pump. In the absence of 
such a cock, the fault can often be discovered by feel- 
ing the pump barrel with the hand. If the pump can 
not be made to work, and the fault is found to be in 
the lower valve, it must be taken out and examined ; or 
if the fault is in the pipes, it can usually be easily 



Accidents to Locomotives. 521 

remedied. If the pipes are burst with only a small 
fracture, it can usually be remedied by covering the 
aperture with canvas or rubber and wrapping twine 
around it tightly. The upper valve of a pump must, 
however, never be taken down without first being sure 
that the check-valve is tight, because if it is not, the 
person will be likely to be scalded in taking the pump 
apart. 

Directions for managing an injector, and also for 
taking care of pumps in cold weather, have already 
been given in the answers to Questions 142 and 488. 

Question 519. What should he done in case of the 
breaking or bursting of a cylinder or cylinder-head 1 ? 

Answer. The main connecting rod -must be taken 
down on that side of the engine. The piston should 
then be moved to the front or back end of the cylinder 
and wooden blocks be placed between the guides so as 
to fill up the space between the cross-head and the 
end of the guide-bars, and thus prevent the cross-head 
and piston from moving. The valve stem should then 
be disconnected from the rocker, and the valve moved 
to the middle of the valve face, so as to cover up both 
steam-ports. It must then be fastened in that posi- 
tion by screwing up one of the bolts of the stuffing- 
box of the valve stem, so as to make the gland bind 
against the valve stem. The train should then be run 
cautiously to the next station with the use of one cyl- 
inder. If the engine is not able to haul the train 
with one cylinder, then it should be uncoupled from 
the train and run to the first telegraph station or 
other point where the aid of a helping engine can be 
obtained or telegraphed for. In the meanwhile the 
train must be protected by the proper signals. Should 
44* 



522 Catechism of the Locomotive. 

the engine continue its journey with one cylinder, it 
must be started, if it should happen to be standing at 
the dead point, by pushing or by means of crow-bars. 
In so doing, however, the bars should not be put be- 
tween the spokes of the wheels, as they may easily be 
caught in the wheels when the engine starts, and in 
this way the spokes be broken or the persons who are 
using the crow-bars be badly hurt. 

Question 520. What must be done in case a steam- 
chest or steam-pipe is broken ? 

Answer. If a steam-chest is broken a block of wood 
should be bolted over the mouth of the steam passage, 
so as to prevent the escape of the steam from the 
steam-pipe on that side. It will sometimes require 
considerable ingenuity to devise means of fastening 
such a block or blocks of wood so as to cover the 
mouth of the steam passage. As cylinders are now 
usually made, the blocks can be fastened by cutting 
them to the proper form and size, and then placing a 
thick block on top, and bolting the steam-chest cover 
down on top of it. If the cover is broken, a part of 
it may be used or a piece of plank with a few holes 
bored into it be employed instead. In some cases a 
piece of board can be bolted over the end of the steam- 
pipe. When the latter is broken, it should be taken 
down and a piece of board or plank bolted over the 
opening of the T-pipe to which the steam -pipe was at- 
tached. The engine can then be run with one cylin- 
der as before, although usually in such cases it is not 
necessary to disconnect any other parts than the valve 
stem. 

Question 521. What must be done if a piston, cross- 
head, connecting-rod or crank-pin is broken or bent f 



Accidents to Locomotives. 523 

Answer. If the piston, cross-head or main connect- 
ing-rod is broken, the same course must be pursued as 
when a cylinder is broken. If a coupling-rod or a 
crank-pin of a trailing- wheel is broken, then it is 
necessary to take down both the coupling-rods, but not 
to disconnect the main connecting-rods or their attach- 
ments, unless they are injured. 

Question 522. If one coupling-rod is broken or taken 
down, why must the other be taken down also f 

Answer. Because if only one rod is used there is then 
nothing to help the cranks of the trailing wheels past 
the dead-points, so that in starting, or if they are 
moving slowly when they reach these points, they are 
quite as likely to revolve in one direction as the other. 
If they happen to turn in the reverse direction to that 
in which the wheels to which they are coupled are 
moving, then the crank-pins of one or the other pair 
of wheels are very liable to be broken or bent. 

Question 523. What must be done if a driving-wheel 
tire or driving-axle breaks f 

Answer. If a tire on a main driving-wheel or the 
wheel itself breaks, the driving-box of the broken 
wheel or tire should be held up by putting a wooden 
block under the box. An ordinary American engine 
can then be run on three driving-wheels, but it must 
be run with the utmost caution. If the engine has 
more than four driving-wheels there is usually less dif- 
ficulty in running it, if one of the main wheels is in- 
jured, than if there are only four. But it is almost 
impossible to give directions which will be applicable to 
all the accidents of this kind that may occur to differ- 
ent kinds of engines. If none of the connecting-rods, 
crank-pins or crank-pin bosses are injured, it is not 



524 Catechism of the Locomotive. 

necessary to disconnect either side, but if the injury 
is of such a nature that the coupling-rod must be 
taken down on one side, the one on the other side 
must be taken down too. If the main crank-pin and 
connecting-rod are not disabled, both cylinders may be 
used even if one of the main wheels or tires is broken. 
But even if one side of the engine must be entirely 
disconnected, the engine may still be run with one 
cylinder and by driving one wheel. If a main axle 
breaks the engine can usually be run, but great cau- 
tion must be exercised. In such cases, however, if 
assistance or a telegraph office is near where the acci- 
dent occurs, it is usually best to send for assistance at 
once, rather than take the risks which attend the at- 
tempt to run an engine so seriously injured. 

Question 524. What must be done when a trailing or 
leading driving-wheel, tire or axle breaks ? 

Answer. Very much the same course must be pur- 
sued as was described in the previous answer, although 
it is generally less difficult to run with a trailing or 
leading axle broken than it is when the main axle has 
met with such an accident. 

Question 525. What must be done if an engine-truck 
wheel or axle breaks ? 

Answer. It is usually best to chain up the end of the 
truck-frame over the broken axle or wheel to the en- 
gine frame and place a cross-tie across the other end 
of the truck-frame, between it and the engine frame, 
so that the weight of the engine may rest on the cross- 
tie. If a part of the flange or a piece of the wheel is 
broken out, the wheels should be turned around so that 
the unbroken part will rest on the rail, and they 
should then be chained or otherwise fastened so that 



Accidents to Locomotives. 525 

they cannot revolve, and thus be made to slide on the 
rails and carry the weight of the engine in that way. 
The same plan is employed if a tender wheel breaks, 
but one end of a tender-truck frame must be chained 
up. It is usually necessary to place a cross-tie across 
the top of the tender, and fasten the chains to it. 

Question 526. What must be done in case a driving- 
spring, spring-hanger or equalizing-lever breaks ? 

Answer. As the breaking of a spring or spring- 
hanger may cause a more serious accident, the engine 
and train should be stopped as soon as possible after 
it occurs. If the hanger is broken and there is a du- 
plicate on hand, it should be substituted in place of 
the broken one. If there is no duplicate, then the 
spring should be taken down, and a wooden block 
be placed between the top of the driving-box and 
the frame to support the weight which before rested 
on the spring. In order to insert this block, if it 
is a front spring which is broken, it is usually best 
to raise the engine with jack-screws or run the back 
wheels on inclined blocks of wood placed under each 
of the back wheels. This raises the weight off from 
the front-wheels, and the block can then be inserted be- 
tween the box and frame. If it is one of the springs over 
the back wheels which is broken, the front wheels should 
be run on the wooden wedges. Such wedges can soon 
be cut out of a cross-tie with an axe, or by sawing a 
square stick of wood diagonally it will make two such 
wedges. The end of the equalizing lever next to the 
broken spring must be supported by inserting a piece 
of wood under it. This will usually be held securely 
by the weight which is suspended from the opposite 
end, bearing the blocked end down on the block. 



526 Catechism of the Locomotive. 

Question 527. What should be done if an engine- 
truck or tender spring breaks ? 

Answer. Very much the same course must be pur- 
sued that is employed when a driving-spring breaks, 
excepting that usually the weight can be lifted off 
from a truck-box easier by placing a jack under the 
end of the truck-frame than by the method described. 
Usually, too, each of the truck-springs supports the 
weight on two of the wheels, so that the two boxes 
must be blocked up. 

Question 528. What must be done in case the engine- 
frame is broken ? 

Answer. Usually very little need be done except- 
ing to exercise more than usual caution in running, 
and to reduce the speed. Of course the breakage of a 
frame may disable the engine, but ordinarily in such 
accidents that is not the case. 

Question 529. How can it be known if an eccentric 
has slipped on the axle ? 

Answer. It is indicated at once by the irregular 
sound of the exhaust, or, as locomotive runners say, 
the engine will be " lame. ,> 

Question 530. When it is known that an eccentric 
has slipped, how can it be learned which is the one that is 
misplaced ? 

Answer. This can usually be learned by examining 
the marks which should always be made on the eccen- 
trics and on the axles. If no such marks have been 
made by the builder of the engine, the runner himself 
should make them, after the valves have been set cor- 
rectly. The effect upon the valve when an eccentric 
slips is either to increase or diminish the lead. There- 
fore, by running the engine slowly with the link first 



Accidents to Locomotives. 527 

in full forward and then in full back gear, and observ- 
ing whether steam is admitted at each end of the cyl- 
inder just before the crank reaches the dead points, it 
can be known which eccentric has moved. If it has 
slipped in one direction the lead will be increased and 
steam will be admitted to the cylinder some time be- 
fore the piston reaches the end of the stroke. If it 
has moved the opposite way, the lead will be dimin- 
ished and steam will not be admitted until after the 
piston has reached the end of its stroke. The admis- 
sion of steam will be indicated by its escape from the 
cylinder cocks. 

Question 531. If by any means the valve stem or 
either of the eccentric rods should be lengthened or short- 
ened, how can it be known f 

Answer. The crank on one side should be placed 
at one of the dead points and the cylinder-cocks 
opened ; then admit a little steam to the cylinder, by 
opening the throttle-valve slightly, and throw the re- 
verse lever from full gear forward to full gear back- 
ward, and observe whether steam escapes all the time 
from the end of the cylinder at which the piston 
stands. Then repeat the operation with the crank at 
the other dead point. If either of the eccentric rods 
or the valve stem have been lengthened or shortened, 
it will cause the valve to cover the steam-port either 
at the front or back end of the cylinder, so that no 
steam will escape from the cock at that end. If the 
length of one of the eccentric rods has been changed, 
then when the altered rod is in gear the valve will 
have too little or no lead at one end of the cylinder 
and too much at the other. If, therefore, this occurs 
when the forward rod is in gear and not in back gear, 



528 Catechism of the Locomotive. 

it indicates that the length of the forward rod has 
been altered. If the reverse occurs it shows that it is 
the back-motion rod whose length has been changed. 
It must be observed that if the length of an eccentric 
rod is altered the lead will be changed only at that 
part of the link which is operated by the altered rod. 
That is, if the forward eccentric rod is too long or too 
short, the lead at the front and back ends of the cylin- 
der in forward gear only will be affected. If the back 
eccentric rod is changed the valve will be affected only 
in back gear. If, however, the length of the valve 
stem is changed, the lead will be changed in both 
forward and back gear. The valves on each side of 
the engine can, of course, be tested in the same way. 

Question 532. When it is discovered which eccentric 
has slipped, how should it be reset f 

Answer. If it has been marked, it is simply turned 
back so that the marks correspond with each other 
again. This is done by first loosening the set-screws, 
and, after the eccentric is turned to the proper place, 
tightening them up again. When an eccentric slips 
it is often caused by the cutting of the eccentric- 
straps, valve or other part of the valve-gear, so that 
these should always be examined to see whether they 
are properly oiled. If the eccentrics have not been 
marked, the valve may be set by placing the crank at 
the forward dead-point, and the reverse lever in the 
front notch of the sector and the full part of the 
forward -motion eccentric above the axle. Then admit 
a little steam into the steam-chest, open the cylinder 
cocks, and move the forward-motion eccentric slowly 
forward until steam escapes from the front cylinder 
cock, which will show that the steam-port is opened 



Accidents to Locomotives. 529 

and the valve has some lead. To set the backward- 
motion eccentric the crank is placed in the same posi- 
tion, but the reverse lever is thrown into the back 
notch and the full part of the eccentric is placed below 
the axle. Then move this eccentric forward until steam 
escapes from the front cylinder cock as before. In 
order to verify the position of the eccentrics the 
crank may be placed at the back dead r point and the 
reverse lever moved backward and forward, at the 
same time observing whether steam escapes from the 
back cylinder cock when the link is in back and for- 
ward gear. 

Question 533. What should be done in case an ec- 
centric-strap or rod, or rocker arm or shaft, or the valve 
stem breaks ? 

Answer. If an eccentric-strap or rod breaks, the 
broken rod and strap should be taken down, and the 
valve-stem disconnected from the rocker and the 
valve fastened in the middle position of the valve 
face, and the engine should be run with one cylinder 
only. The same course must usually be pursued if a 
rocker breaks. If the valve-stem breaks, it is not 
necessary to disconnect the link and eccentric rods, 
but simply to fasten the valve in the centre of the 
valve face. 

Question 534. If a link hanger or saddle, or a lift- 
ing arm should breaks what may be done ? 

Answer. The valve-gear may be used on that side 
of the engine by putting a wooden block in the link 
slot above the link block, so as to support the link 
near the position at which it works the valve full 
stroke forward. Of course the engine can then be 
run in only one direction, and should therefore be 
45 



530 Catechism of the Locomotive. 

run with the utmost caution. If, however, it should 
be necessary to back the train on a side track, it can 
be done by taking out the wooden block and substi- 
tuting a longer one, so that the link will be supported 
in a position near that at which it works the valve full 
stroke backward. These blocks must be fastened in 
some way, either with rope or twine, so that they will 
be held in thejr position when the engine is at work. 

Question 535. If the lifting shaft itself or its verti- 
cal arm, the reverse lever or rod, should break, what can 
be done t 

Answer. If it is impossible to devise any temporary 
substitute or method of mending them, both links can 
be blocked up as described above. 

Question 536. In case the throttle-valve should fail, 
what should be done ? 

Answer. If such an accident occurs, especially if it 
happens about a station, it is attended with great 
danger.^ If it is found that steam can not be shut off 
from the cylinders with the throttle-valve, then the 
reverse lever should be placed in the middle of the 
sector. If this does not prevent the engine from 
moving, the reverse lever should be alternately 
thrown into forward and then into back gear, and 
at the same time every aperture, such as the safety- 
valve and heater cocks, should be opened, and every 
means be taken to cool the boiler as quickly as possi- 
ble. The fireman should open the furnace door, close 
the ash-pan dampers, and start the blower so as to 
draw a strong current of cold air into the furnace 
and through the tubes. At the same time the injec- 
tor should be started and the fire drawn as quickly as 
possible. After the boiler is cooled, the cover of the 



Accidents to Locomotives. 531 

steam-dome may be removed and the valve examined 
if the defect can not be discovered in any other way. 
Of course if the accident occurs on the open road, the 
train must be at once protected by sending out sig- 
nals in each direction. 

Question 537. What must be done in case a coupling 
breaks ? 

Answer. When a coupling between the cars or ten- 
der breaks, if the front end of the train is immedi- 
ately stopped, there will be danger that the back end 
of it, which is broken loose, will run into the front 
end, and thus do great damage. As it always occurs, 
when a coupling of a passenger train breaks, that the 
signal bell in the cab is rung, the first impulse of a 
runner under such circumstances is to stop the engine. 
He should, however, be careful not to do so if on shut- 
ting off steam he finds that the train has broken in 
two, but should at once open the throttle in order to 
get the front end of the train out of the way of the 
rear end. The ease with which the speed of a train 
is arrested with continuous brakes has increased the 
danger of accident from this cause. Usually a runner 
learns by the sudden start of the engine that the train 
has separated, and when that occurs he should never 
apply the brakes. 

Question 538. If from any cause the supply oj 
water in the tender becomes exhausted, what must be 
done? 

Answer. It is best, if it can be done without risk of 
injury to the engine, to run the train on a side track 
and then draw the fire. If no water can be obtained 
near enough to supply the tender with buckets, help 
must be sent for; but if there is a well, stream or 



532 Catechism of the Locomotive. 

pond of water near, the tender can be partly filled 
by carrying water. 

Question 539. In case an engine becomes blockaded 
in a snow storm with plenty of fuel, but runs out of 
water, what can be done ? 

Answer. Snow should be shoveled into the tender 
and steam admitted through the heater cocks so as to 
melt the snow. 

Question 540. If a locomotive without an injector 
should be obstructed in a snow storm or in any other way 
so that it could not move, and therefore could not work 
the pumps, what should be done in case the water in the 
boiler should get low ? 

Answer. The weight of the engine should be lifted 
off from the main driving-wheels and the coupling 
rods disconnected from the main crank-pin, so that 
the main wheels can turn without moving the engine. 
These can then be run and the pumps thus be worked. 
The weight can usually be most conveniently taken 
off from the main wheels by running the trailing 
wheels on wooden blocks, and thus raising up the 
back end of the engine. 

Question 541. If it is impossible, in a snow storm 
or in very cold weather, to keep steam in the boiler without 
danger, what should be done ? 

Answer. Draw the fire, blow all the water out of the 
boiler, empty the tanks, disconnect the hose and 
slacken up the joints in the pumps and injector so 
that all the water in them can escape, and thus pre- 
vent them from freezing up. 



PAKT XXIX. 
ACCIDENTS AND INJURIES TO PERSONS. 

Question 542. In case an accident occurs and one 
or more persons are seriously injured, what can be done 
by those present ? 

Answer. In such cases it very often happens that 
with knowledge and sufficient coolness to apply that 
knowledge, one or more non-medical persons who are 
present when an accident occurs can do as much or 
more toward saving life and allaying pain, before a 
doctor comes, than he can afterwards. The following 
cases cited by Dr. Howe in his book on " Emergen- 
cies " will illustrate this : 

"Case 1. — A machinist was admitted to a New 
York hospital suffering from wounds of the wrist and 
palm of the hand. On arriving at the hospital the 
entire clothing on one side of his body was saturated 
with blood, from the loss of which he was partly in- 
sensible. On making an examination, it was found 
by the surgeon that a folded handkerchief was ban- 
daged over the centre of the wrist, and that the 
wound in the palm of the hand was untouched. The 
pad was placed on the wrist, as if the greatest care 
had been exercised to avoid pressing on either of 
the two arteries. The bleeding in this case could 
easily have been controlled if the bandage and pad 
had been properly applied. The patient, however, 
45* 



534 Catechism of the Locomotive, 

developed erysipelas, and, not having sufficient vital- 
ity to carry him through, died the fifth day." 

" Case 2. — A laborer fell from the front platform of 
a car at Harlem, and had his right foot crushed by 
one of the wheels. An ordinary bandage was placed 
on the limb without any compress over the vessels. 
In bringing the man to the hospital, the rough jolting 
of the carriage set the wound bleeding, and by the 
time he reached his destination he was apparently 
lifeless. The vessels were tied and stimulants ad- 
ministered, but he never rallied. Death occurred 
six hours after his admission. His injuries, inde- 
pendent of the bleeding, might indeed have termin- 
ated his life ; still the chances would have been in 
his favor if a compress had been applied to the limb 
to prevent bleeding. The fact that such a thing was 
not done shows either culpable negligence or deplora- 
ble ignorance." 

Many similar cases constantly occur where a little 
intelligent timely action of those present would save 
the life of an injured person, who without such help 
must die before professional surgical aid can be ob- 
tained. 

Question 543. When it is found (hat one or more 
persons are seriously injured, what is the first thing to be 
done? 

Answer. The first thing to do is to extricate the 
person or persons from the danger, and at the same 
time send a messenger for a doctor. If it is doubt- 
ful if one can be obtained by sending in one direc- 
tion, send two or more messengers in different di- 
rections. 

Question 544. To what kind of injuries are locomo- 



Accidents and Injuries to Persons. 535 

tive runners and other persons employed or traveling on 
railroads exposed ? 

Answer. They are liable to be bruised or crushed in 
case of collision or running off the track, or of injury 
from falling off the train, or of being run over by a 
moving train. Brakemen and others whose duty it is 
to couple cars are liable to have their hands, arms or 
bodies crushed between the cars, and locomotive run- 
ners are sometimes burned or scalded if an accident 
happens to their engines. Train-men are also fre- 
quently exposed to very great cold in winter and heat 
in summer, and are thus liable to be frost-bitten or 
sun-struck. Passengers are seldom injured excepting 
through their own carelessness, unless in cases of col- 
lision or running off the track and the destruction of 
the cars. Strangers and even railroad employes are 
frequently run over by trains while walking on the 
track, and frequent accidents occur to deaf people in 
this way, and it is not very unusual to hear of train- 
men who sit on the main track at night while their 
trains are waiting on the side-track for another train 
to pass, go to sleep while in that position, and then 
are run over by the passing train. 

Question 545. When persons are crushed or danger- 
ously wounded, what are the chief immediate sources of 
danger and death when their wounds are not necessarily 
fatal? 

Answer. First, excessive bleeding in case an artery 
is ruptured; second, the shock to the whole system, 
from which the sufferer may not have the strength to 
recover. 

Question 546. When does bleeding from a wound be- 
come dangerous ? 



536 Catechism of the Locomotive, 

Answer. Profuse bleeding is always dangerous, but 
it should be remembered that bleeding occurs from 
two sources : first from the arteries, which are the ves- 
sels which convey the blood from the heart, and second 
from the veins, through which the blood flows back to 
the heart. The first is called arterial bleeding and the 
second venous bleeding. Now it must be remembered 
that the heart is the great force-pump of the body, 
and that it supplies all parts of the body with blood, 
somewhat as the feed-pump of a locomotive supplies 
the boiler with water. The arteries referred to fulfill 
the same purpose that the feed-pipe does to a locomo- 
tive pump — they convey the fluid from the pump 
to the place where it is needed. Now the blood is 
forced into these arteries with a certain amount of 
pressure, so that if any of them are cut or injured the 
blood will flow out in a jet or spurt just as the water 
will escape from a feed-pipe if that is ruptured. The 
blood which flows through the veins back to the heart 
may, on the other hand, be compared to the water in 
the supply pipes of a locomotive pump, that is, there 
is very little pressure on it, and therefore if they are 
injured the flow of blood from them is less rapid than 
from the arteries. It will therefore be seen that arte- 
rial bleeding is much more dangerous, because the 
blood flows from them under a pressure. 

Question 547. How can arterial bleeding be distin- 
guished from venous bleeding ? 

Answer. The blood is of a bright scarlet color, and is 
forced out in successive jets; each jet corresponds 
with the movements of the heart. This characteristic 
spurting is caused by the intermittent force-pump 
action of the heart, driving out the blood. Venous 



Accidents and Injuries to Persons. 537 

bleeding is distinguished from arterial by the dark- 
blue color of the blood when flowing from the wound. 
It never flows in repeated jets, but oozes slowly from 
the wounded surfaces. Venous blood is traveling to- 
ward the heart, and there is consequently little force 
behind to cause a more rapid flow. This form of 
bleeding is comparatively harmless, unless occurring 
from very large veins.* 

Question 548. How can the bleeding be stopped in 
case an artery is cut or ruptured ? 

Answer. The most efficient and available method is 
the application of pressure on the artery between 
the wound and the heart. Under ordinary cir- 
cumstances this can be most effectively done with what 
is called afield tourniquet, which is simply a handker- 
chief passed around the limb above the wound, the 
ends of which are then tied together. A pad is then 
made, either of cloth rolled up, a piece of wood, or a 
round stone about the size of a hen's egg well wrapped, 
or any substance from which a firm pad can be quick- 
ly made, which is placed over the artery. The hand- 
kerchief is then placed over the pad and a short stick 
put through it on the opposite side of the limb and 
twisted around until the pad compresses the artery 
firmly. While the tourniquet is being prepared, some 
one should compress the artery with his fingers or 
thumb, so as to prevent as much loss of blood as pos- 
sible. 

Question 549. What is the position of the arteries in 
the body and how can their location be known ? 

Answer. The position of the principal arteries is 



* " Emergencies and How to Treat Them," by Joseph W. Howe, 
M. D. 




Fig. 230. 



Accidents and Injuries to Persons. 539 

shown in fig. 230. They proceed from the heart h 
with branches, a, a, and b, b, which extend along each 
limb. These branches subdivide again below the 
knees and elbows, and again in the hands aDd feet. 
The position of the arteries can be felt by their pulsa- 
tion at almost any part of them, but when they are 
buried below the muscles it is more difficult than when 
they are near the surface. 

Question 550. In case of a wound and rupture of the 
arteries in the arm, what should be done f 

Answer. The artery at a should be firmly com- 
pressed with the thumb until a bandage and pad from 
which a tourniquet can be made are prepared. The 
pad should then be applied over the artery and com- 
pressed as explained in answer to Question 548. The 
bleeding can also be stopped by placing a round piece 
of wood or other form of pad between the arm at a 
and the body and then tying the arm tightly against the 
body, so that the pad will be pressed against the arm. 

Question 551. In case of rupture to an artery below 
the knee, where should the pressure be applied? 

Answer. The artery approaches near the surface at 
c, c, immediately back of the knee, where it is repre- 
sented in dotted lines in fig. 230. Pressure should there- 
fore be applied at that point first with the thumb until 
a tourniquet can be applied. The bleeding can also be 
stopped by elevating the leg and allowing it to rest 
on the back of a chair or other similar support. The 
weight of the leg will then bring sufficient pressure 
on the artery to stop the bleeding. A towel or other 
soft material should be placed over the back of the 
chair, so that the pressure will not be too painful to 
the sufferer. 



540 Catechism ~of the Locomotive. 

Question 552. If an artery is ruptured in the leg 
above the knee, where should the pressure be applied ? 

Answer. In the thigh at b, where the beating or 
pulsations in the artery can he 'distinctly felt. The 
reader should familiarize himself with the position of 
the arteries by feeling their location in his own body. 
By doing so he may be able to save the life of a com- 
panion or other person in case of accident, whereas 
without such knowledge the injured person would die. 

Question 553. After the arterial bleeding has been 
stopped, if blood should continue to ooze out of the wound, 
what should be done ? 

Answer. The wound should be filled with lint or 
cotton waste ; and the limb then be bandaged by be- 
ginning at its extremity and wrapping the bandage 
closely and evenly around it so as to bring, as nearly 
as possible, an equal pressure on the whole of it. 
Bandaging the limb in this way up to the point 
where the pressure is applied to the artery, will pre- 
vent swelling, and the veins will be compressed so 
that the blood will not flow from their torn extremi- 
ties. 

Question 554. When the bleeding has been stopped, 
what should be done ? 

Answer. The injured person should be laid in as 
comfortable a place as can be procured for him, and 
should be given a moderate drink of water. If much 
exhausted, two or three tablespoonsful of brandy or 
whisky, mixed with an equal quantity of water, 
should be given first, and smaller quantities, of not 
more than A tablespoonful at a time, should 
then be given every half hour. Usually wounded 
persons are given too much stimulant, so that fre- 



Accidents and Injuries to Persons. 541 

quently they are injured more than they are benefited 
thereby. 

After a person has lost much blood, he feels an in- 
tolerable thirst, but if too much water is given him, 
he is apt to become sick and vomit, which weakens 
him still more. It is therefore best to give him very 
little water, say a teaspoonful at a time, after the first 
drink, or if ice can be obtained, give the sufferer 
pieces of ice frequently, which can be allowed to melt 
slowly in his mouth. 

Question 555. When a person is insensible, what 
should be done for him f 

Answer. Lay him down in as comfortable a place as 
the circumstances will permit, and protect him from 
cold, rain or hot sun, as may be needed. A common 
error is to place injured and insensible persons in an 
erect position or in a chair. If he is insensible he 
should always be laid down with his head slightly 
lower than his body. Then water should be dashed 
two or three times on his face, and warm bricks, stones 
or pieces of iron, such as coupling links or pins, ap- 
plied to his feet and in the arm-pits and between the 
thighs, being "careful that the warm objects applied 
are not hot enough to burn. Then cover the person 
with blankets, heavy coats or anything else which 
will keep him warm. Wounded persons soon be- 
come cold and chilled, the effects of which are very 
injurious, and therefore especial pains should be taken 
to keep them warm. In very cold weather there is 
great danger that injured persons will be frost-bitten, 
which must be carefully guarded against. 

In case of shock, when the injured person lies pale, 
faint, cold and sometimes insensible, with feeble 
46 



542 Catechism of the Locomotive, 

pulse and labored breathing, anything like excitement 
must be avoided, as it tends to exhaust the patient. 

All assistance and attention should be given to 
a wounded person with the least noise and excitement, 
and all crowds and idle spectators should be driven 
away aud every effort made to keep the sufferer com- 
fortable and quiet. If food is given it should be in 
the form of beef tea or broth, and in small quantities 
at a time. 

Question 556. In case any bones are broken, what 
should be done ? 

Answer. The limb should be supported as comforta- 
bly as possible until a doctor's services can be ob- 
tained. There is danger with a broken limb that the 
bones will protrude through the flesh and skin, to 
avoid which the limb should be placed in a natural 
position and laid on a pillow, car cushion or other soft 
object. This should then be wrapped around the 
limb and tied in this position, so as to prevent any 
movement of the broken bones. 

Question 557. If a person is crushed or severely 
burned, what should be done f 

Answer. The immediate danger from such injuries 
arises from the " shock " to the system. It is usually 
best to bandage the part which is crushed until sur- 
gical aid can be obtained, and the sufferer treated as 
explained in answer to Question 548. 

Question 558. What should be done for a person 
who has been burned or scalded ? 

Answer. Lint or cotton waste saturated with mo- 
lasses and water should be applied to the wound, or the 
latter should be dusted with wheat flour, and then 
dressed with lint or cotton waste, and loosely bandaged. 



Accidents and Injuries to Persons. 543 

If the injury should be severe, a shivering followed by 
depression is very likely to come on. To check this, 
warmth in the form of hot applications and stimulants 
should be used, as already explained. 

Question 559. What should be done for a frost-lite? 

Answer. Warmth should be applied to the frozen 
part very gradually by rubbing with snow or pouring 
cold water on it. The occurrence of stinging pain, 
with a change in color, is a signal to stop all rubbing 
or other measure which might excite inflammation. 
If the frozen part turns black the next day, a poultice 
'should be applied. 

If persons exposed to the cold become very much 
exhausted or sleepy, stimulants should be given, as 
explained in answer to Question 554, and the body 
briskly rubbed with the hands and warm flannel or 
other woolen material. 

Question 560. How should a person be treated who 
has been sun-struck f 

Answer. Apply cold water or ice to the head, place 
the sufferer in a cool place, and make him comfort- 
able. After being sun-struck the person should not 
work for some days or weeks thereafter, until his 
health and strength are fully recovered. 



PART XL. 

RESPONSIBILITY AND QUALIFICATIONS OF 
LOCOMOTIVE RUNNERS * 

Question 561. What are the dangers to which the 
runner and the fireman are exposed by their work on the 
engine f 

Answer. Runners and firemen are not only exposed 
to great bodily injury or even death by every accident 
which may happen to their engine, but unless they are 
very careful to preserve their health it is quickly de- 
stroyed by the constant changes of the weather to which 
their position exposes them, and also by the effect of 
the heat of the fire and by the smoke by which they 
are often surrounded. 

In order to protect themselves in a measure from 
the injurious effects of change of weather, smoke, cold, 
etc., frequent bathing and cleansing of the skin are ab- 
solutely necessary, and also the wearing of a woolen 
undershirt next the skin at all seasons. 

The gases of coal which pour out of the furnace- 
door, if it is opened when the throttle is closed, have 
an especially injurious effect on the throat, lungs, etc. 
They should always see to it, therefore, that the 
blower is always started before the fire-door is opened, 
in order that these injurious gases, which have col- 



* Note.— The greater part of this chapter is a translation from Prof. 
George Kosak's " Katechismus der Einrichtung und Betriebes der Lo^- 
comotive." 



Qualifications of Locomotive Runners. 545 

lected during a halt, may be drawn forward and up 
the smoke-stack by the draft. 

The steady, loud clatter which the engine makes 
while running has an injurious influence on the ner- 
vous system. The runner should therefore endeavor 
to lessen these shocks of the engine as far as possible 
by keeping watch over it and keeping its parts accu- 
rately adjusted. In order to keep himself fresh and 
strong in his service, which is extremely exhaustive 
to body and mind, the runner must try to strengthen 
himself by regular, temperate living, and eating abun- 
dant nourishing food. The common use of strong 
drinks, which undermines the mental and physical 
strength of men, should be avoided by a person occu- 
pying the exhaustive and responsible position of a 
locomotive runner. If in ordinary life a drunken man 
is unfit for any simple work, how shall a drunken run- 
ner or fireman undertake the difficult management of 
so great, so delicate and so costly a machine as a loco- 
motive ? How can hundreds of men quietly trust 
their lives and limbs to such a man, whom no one 
can help despising ? Rightfully, therefore, conscien- 
tious railroad managers place the greatest stress on 
the sobriety of the runners and firemen, and instantly 
discharge from their service those who give them- 
selves up to a passion for drink. 

Owing to the demands which their daily labor 
makes upon their strength and endurance, locomotive 
runners should be careful not to increase the drain by 
dissipation, irregular hours or overwork. There seems 
to be something about the power of endurance of the 
human frame analogous to the capacity of a bar of iron 
or steel to resist strains. So long as the strains do 



46 



546 Catechism of the Locomotive. 

not exceed the elastic limit, that is if the bar recovers 
its original length when the strain is removed, it will 
bear millions of such strains without becoming weak- 
er; but if it is strained so hard that it is permanently 
stretched, then comparatively few applications of the 
force will rupture the bar. In a similar way, if the 
strain or fatigue which a man endures is no more than 
he will recover from after the ordinary rest, he can 
endure an almost unlimited number of such strains, 
but if the fatigue exceeeds his " elastic limit," then he 
soon becomes permanently injured thereby. It often 
happens that an excessive amount of work is unavoid- 
able, but when it can be avoided it should be by those 
who wish to preserve their health and strength. 

In order to save themselves from great injuries, 
runners and firemen should always act with the 
greatest caution, and never rush carelessly into dan- 
ger. They should never adopt the principle of fool- 
hardy and thoughtless people, who by the conscious- 
ness of continual danger fall into the habit of care- 
lessly " trusting to their luck," etc. On the contrary, 
they should always face the danger with their eyes 
open and with the greatest conscientiousness. Many 
try to show great courage by scorning the danger, and 
some such even wish to meet a little in order to be 
able to show their pluck. These should bear in mind 
that they have a great responsibility laid upon them, 
and that it is not alone their own well-being or life 
which is at stake in case of any mishap, but that by 
their careless behavior they may wound or kill the 
helpless people who are committed to their care, 
cause incalculable misery by robbing families of their 
sole support and of their children ; and bring great 



Qualifications of Locomotive Runners. 547 

sorrow and mourning to their fellow-men. The 
thought of the curse and the despair of the survivors 
may give sleepless hours even to a locomotive runner 
who knows himself to have been without any fault 
regarding an accident ; how much more must it be 
with him who cannot give himself this assurance? 
There are not wanting instances in which the runner 
who caused such an accident by his thoughtlessness, 
driven to despair by his own heavily-burdened con- 
science, went miserably to ruin. 

Question 562. What requirements and duties should 
every locomotive runner fulfill? 

Answer. Every locomotive runner should fulfill the 
following requirements and duties : 

1. He should have an exact knowledge of the en- 
gine intrusted to him, and a general- knowledge of the 
nature and construction of steam engines generally. 
Likewise, he should be perfectly familiar with the 
management of the boiler, the running of the engine, 
and the way of keeping the working parts in good 
condition ; also, with the forms and peculiarities of 
the line of road on which he runs, the rules which 
govern the running of trains and with the signal sys- 
tem adopted. 

2. Health and bodily strength he must have in abund- 
ant measure in his position, which is exhausting and 
in which he is exposed to all sorts of weather. 

3. He should have a good, plain common-school edu- 
cation, and be ready at reading, writing and arith- 
metic. 

4. He should always carry out exactly and cheerfully 
the regulations of the service, or the instructions given 
him by special orders from the officers over him. 



548 Catechism of the Locomotive. 

5. Faithfulness, frankness and honesty, which charac- 
terize an upright man in ordinary life, and also the 
strictest temperance in the use of strong drink, he 
should possess in a high degree in his very responsible 
position. 

6. He should have acquired a certain degree of skill 
in putting together and taking apart locomotives, and 
also in repairing separate parts of them. It is desira- 
ble that he should always be present when his own 
engine is taken apart, put together or repaired, in or- 
der that he may acquire a thorough knowledge of its 
condition and learn to understand properly the im- 
portance of its various parts. 

7. In caring for his engine he must preserve perfect 
cleanliness and order, and in using fuel he must mani- 
fest the greatest care and rigid economy. 

8. Whenever there is danger, coolness and self- 
possession are indispensably necessary, and any 
thoughtlessness or recklessness is to be strictly 
avoided. 

9. Towards his superior officers his behavior should 
be respectful and obliging ; towards those under him, 
patient and kindly, and at all times he should avoid 
profanity and all intemperate language. He should 
endeavor, as far as possible, to instruct the fireman 
who accompanies him and make him familiar with 
the construction and management of the engine, and 
should see that he does his work strictly in accordance 
with his instructions. 

It is the fireman's duty to follow the runner's in- 
structions strictly, and in case of any sudden disa- 
bility of the runner he must stop the engine in accord- 
ance with the instructions given him, and then give 



Qualifications of Locomotive Runners. 549 

the proper signals for help, until another runner ar- 
rives. In the meanwhile the engine is to be kept at 
a halt with all the usual precautions. 

10. The runner should try to keep himself informed 
of the progress and improvement of locomotives by 
reading suitable books and technical periodicals, and 
when possible acquire some skill in geometrical and 
mechanical drawing, in order to accustom himself to 
accurate work and sound and systematic thinking. 

Question 563. What studies should mechanics, loco- 
motive runners and firemen take up, and what technical 
books should they read ? 

Answer. As already stated, they should know how 
to read and write their own language, and understand 
arithmetic and have some knowledge of geography. 
Every locomotive runner and fireman has a good deal 
of spare time, a part of which he can devote to study, 
and all of them, even if they have not had the advan- 
tage of early education, could by industry and perse- 
verance acquire a knowledge of lt reading, writing and 
ciphering." The assistance of a good teacher should 
always be procured, if possible. With so much knowl- 
edge, some book on natural philosophy can be read 
to advantage, and then some book on mechanics. The 
following list of books is given, which the student will 
do well to read in the order in which they are named. 
It should always be remembered, however, that the 
mere buying of books contributes very little knowl- 
edge to the owner. It is the reading and understand- 
ing them which " increases knowledge." 



550 Catechism of the Locomotive. 



LIST OF BOOKS FOR MECHANICS, LOCOMOTIVE RUNNERS. 
FIREMEN, ETC. 

A Hand Book of the Steam Engine, by John Bourne ; published by 
Longmans, London ; $2.00. 

A Catechism of the Steam Engine, by John Bourne ; published by 
Longmans, London; $2.00. 

Lessons in Elementary Physics, by Balfour Stewart; published by 
Macmillan & Co., New York; $1.50. 

Experimental Mechanics, by Prof. Ball; published by Macmillan & 
Co., New York; $6 00. 

The New Chemistry, by Prof. J. P. Cooke; published by Appleton & 
Co., New York; $2 00. 

Elementary Treatise on Heat, by Balfour Stewart; published by 
Macmillan & Co , New York; $3.00. 

Combustion of Coal, by C. Wye Williams ; published by Lockwood & 
Co , London; $1.20. 

A Treatise on Steam Boilers, by Robert Wilson ; published by Lock- 
wood «fe Co., London; $3.00. 

Link-Valve Motion, by Wm. S. Auchincloss; published by D. Van 
Nostrand, New York ; $3.00. 

The Conservation of Energy, by Balfour Stewart; published by Ap- 
pleton & Co., New York; $1.50. 

Richards' Steam Engine Indicator, by Charles T. Porter ; published 
by Longmans, London ; $2.50. 



( 



PL A T E S 



DIMENSIONS, WEIGHT, ETC., 

OF 

FOUR-WHEELED SWITCHING LOCOMOTIVE, 

By the Hinkley Locomotive Works. Boston, Mass. 



Gauge of Road 4 ft. %% in . 

Number of Driving- Wheels 4 

Number of Front Truck- Wheels None. 

Number of Back Truck- Wheels None . 

Total Wheel Base 6 ft. 9 in. 

Distance between Front and Back Driving- Wheels 6 ft. 9 in . 

Total Weight of Locomotive in working order 48,000 lbs. 

Total Weight on Driving- Wheels 48,000 lbs . 

Diameter of Driving- Wheels 50 in. 

Diameter of Truck- Wheels None . 

Diameter of Cylinders 15 m. 

Stroke of Cylinders 22 

Outside Diameter of smallest Boiler ring 44^ in . 

Size of Grate 3 X 3% ft. 

Number of Tubes 121 

Diameter of Tubes 2 in . 

Length of Tubes 10 % ft. 

Square Feet of Grate surface -. 11 

Square Feet of Heating surface in Fire-Box 71 

Square Feet of Heating surface in Tubes . . . - 580 

Total Feet ot Heating surface 651 

Exhaust Nozzles — single or double Double. 

Diameter of Nozzle 2.% in 

Size of Steam Ports 10 X 1 % in . 

Size of Exhaust Ports 2% in . 

Throw of Eccentrics 4/^ m - 

Outside Lap of Valve & in- 
Inside Lap of Valve None . 

Size of Main Driving-axle Journal 6% X 7 in . 

Size of other Driving-axle Journal 6% X 7 in. 

Size of Truck-axle Journal None . 

Diameter of Pump Plunger x% in. 

Stroke of Pump Plunger 22 in . 

Capacity ot Tank 1,200 gallons. 



5§4 



Plats v. 

DIMENSIONS, WEIGHT, ETC, 

OF 

EIGHT-WHEELED "AMERICAN" LOCOMOTIVE 
By the Baldwin Locomotive Works, Philadelphia. 



Gauge of Road 4 ft. 8J£ in. 

Number of Driving- Wheels 4 

Number of Front Truck- Wheels 4 

Number of Back Truck- Wheels None. 

Total Wheel Base 21 ft 9 in. 

Distance between centres of Front and Back Driving- Wheels . . .96 in. 

Total Weight of Locomotive in working order 65,000 lbs. 

Total Weight on Driving- Wheels 42,000 lbs. 

Diameter of Driving- Wheels 6o2£ in. 

Diameter of Truck Wheels 28 in. 

Diameter of Cylinders 16 in. 

Stroke of Cylinders 24 in. 

Outside Diameter of smallest Boiler Ring 48 i*. 

Size of Grate 65 X 34K in - 

Number of Tubes 144 

Diameter of Tubes 2 in. 

Length of Tubes 10 ft. n in. 

Square Feet of Grate surface 15.5 

Square Feet of Heating surface in Fire-Box 100.6 

Square Feet of Heating surface in Tubes 825.4 

Total Feet of Heating surface 926 

Exhaust Nozzles — single or double Double. 

Diameter of Nozzle 2^ to 3% in. 

Size of Steam Ports i%" X 15 in. 

Size of Exhaust Ports 2% X 15 in. 

Throw of Eccentrics 5% in. 

Outside Lap of Valve & to- 
Inside Lap of Valve 1-32 in. 

Size of Main Driving-axle Journal 7 in. dia. X 8 in. 

Size of other Driving-axle Journal 7 in. dia. X 8 in. 

Size of Truck-axle Journal 4^ X 7% in. 

Diameter of Pump Plunger 2 in. 

Stroke of Pump Plunger 24 in. 

Capacity of Tank 2,000 g&Boo*. 



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556 



Plate vl 

DIMENSIONS, WEIGHT, ETC., 

OF 

EIGHT-WHEELED "AMERICAN" LOCOMOTIVE 
By the Grant Locomotive Works, Paterson, N. J. 



Gauge of Road 4 ft. %% in. 

Number of Driving- Wheels 4 

Number of Front Truck- Wheels 4 

Number of Back Truck- Wheels None. 

Total Wheel Base 21 ft. 9 in. 

Distance between centres of Front and Back Driving- Wheels 8 ft. 

Total Weight of Locomotive in working order 62,000 lbs. 

Total Weight on Driving- Wheels 42,000 lbs. 

Diameter of Driving- Wheels 61 in . 

Diameter of Truck-Wheels 28 in . 

Diameter of Cylinders 16 in. 

Stroke of Cylinders 24 in . 

Outside Diameter of smallest Boiler Ring 48 in. 

Size of Grate 60 x 34 in. 

Number of Tubes 140 

Diameter of Tubes 2 in . 

Length of Tubes 11 ft. 

Square Feet of Grate surface 14 

Square Feet of Heating surface in Fire-Box 98 

Square Feet of Heating surface in Tubes 805 

Total Feet ©f Heating surface 903 

Exhaust Nozzles — single or double Double. 

Diameter of Nozzle 3 j£ to 3% in . 

Size of Steam Ports 1 J^ X 14 in . 

Size of Exhaust Ports 2.% x 14 in. 

Throw of Eccentrics 5 in . 

Outside Lap of Valve % in. 

Inside Lap of Valve None. 

Size of Main Driving-axle Journal 6% dia. X 7% in. 

Size of other Driving-axle Journal 6% dia. X j% in. 

Size of Truck-axle Journal 4^ dia. X 8 in. 

Diameter of Pump Plunger 2 in. 

Stroke of Pump Plunger 24 in. 

Capacity of Tank 2,000 gallons. 



558 



Plate vii. 



DIMENSIONS, WEIGHT, ETC., 

OF 

EIGHT-WHEELED "AMERICAN" LOCOMOTIVE 

BY THE 

Danforth Locomotive and Machine Co., Paterson, N. J. 



Gauge of Road 4 ft. 8^ in . 

Number of Driving- Wheels 4 

Number of Front Truck- Wheels 4 

Number cf Back Truck-Wheels None. 

Total Wheel Base 21 ft. 2 in. 

Distance between centres of Front and Back Driving- Wheels, 7 ft. 9 in. 

Total Weight of Locomotive in working order. 60,200 lbs. 

Total Weight on Driving- Wheels 38,350 lbs. 

Diameter of Driving- Wheels 5 ft. 7^ in. 

Diameter of Truck- Wheels -. 2 ft. 6 in . 

Diameter of Cylinders 15 in. 

Stroke of Cylinders 24 in. 

Outside Diameter of smallest Boiler Ring 3 ft. 10 in. 

Size of Grate 56 x 34K in. 

Number of Tubes 136 

Diameter of Tubes 2 in. 

Length of Tubes 11 ft. 

Square Feet of Grate surface 13.5 

Square Feet of Heating surface in Fire-Box 86 

Square Feet of Heating surface in Tubes 775 

Total Feet of Heating surface 861 

Exhaust Nozzles — single or double Double. 

Diameter cf Nozzle 2^ in . 

Size of Steam Ports x% X 13K in. 

Size of Exhaust Ports 2%, X 13^ in. 

Throw of Eccentrics 5^ in . 

Outside Lap of Valve % in. 

Inside Lap of Valve % in • 

Size of Main Driving-axle Journal 6% in. 

Size of other Driving-axle Journal 6% in . 

Size of Truck-axle Journal 4% in. 

Diameter of Pump Plunger 2% in. 

Stroke of Pump Plunger = 24 in. 

Capacity of Tank x,8ooi 



Plate viii. 
DIMENSIONS, WEIGHT, ETC., 

OF 

EIGHT-WHEELED "AMERICAN" LOCOMOTIVE 

By the Mason Machine Works, Taunton, Mass. 

Gauge of Road „ 4 ft. 8% in. 

Number of Driving-Wheels 4 

Number of Front Truck- Wheels „ 4 

Number of Back Truck-Wheels None. 

Total Wheel Base 22 ft. 

Distance between centres of Front and Back Driving- Wheels .... 8 ft. 

Total Weight of Locomotive in working order 62,000 lbs. 

Total Weight on Driving- Wheels 40,000 lbs. 

Diameter of Driving- Wheels 5 ft. 6 in. 

Diameter of Truck- Wheels 2 ft 9 in. 

Diameter of Cylinders , 1 ft. 5 in. 

Stroke of Cylinders 2 ft. 

Outside Diameter of smallest Boiler Ring 3 ft. 10 in.* 

Size of Grate 66 X 35% in. 

Number of Tubes 155 

Diameter of Tubes , 2 in. 

Length of Tubes 11 ft. 2 in. 

Square Feet of Grate surface 16. 38 

Square Feet of Heating surface in Fire-Box 105 

Square Feet of Heating surface in Tubes 906 

Total Feet of Heating surface ion 

Exhaust Nozzles — single or double Single. 

Diameter of Nozzle. 3^ in. 

Size of Steam Ports 15 X 1 % in. 

Size of Exhaust Ports 15 X 2% in. 

Throw of Eccentrics 4^ in. 

Outside Lap of Valve % in. 

Inside Lap of Valve 1-16 in. 

Size of Main Driving-axle Journal 6% X 7^ in. 

Size of other Driving-axle Journal 

Size of Truck-axle Journal 3^ X 6 % in. 

Diameter of Pump Plunger x% in. 

Stroke of Pump Plunger 24 in. 

Capacity of Tank 2,250 gallons. 

* The Boiler is made conical, 46 in. diameter at the Smoke-Box and 
50 in. at the Fire-Box. 



561 




Plate ix. 



DIMENSIONS, WEIGHT, ETC., 

OF 

EIGHT-WHEELED "AMERICAN" LOCOMOTIVE 

BY THE HlNKLEY LOCOMOTIVE WORKS, BOSTON, MASS. 



Gauge of Road 4 ft. %% in. 

Number of Driving-Wheels 4 

Number of Front Truck-Wheels 4 

Number of Back Truck- Wheels None. 

Total Wheel Base 21 ft. 4^ in. 

Distance between centres of Front and Back Driving- 

Wheels 7 ft. 6 in. 

Total Weight of Locomotive in working order 63,000 lbs. 

Total Weight on Driving- Wheels 41,000 lbs. 

Diameter of Driving- Wheels 68 in. 

Diameter of Truck- Wheels , 30 in. 

Diameter of Cylinders 16 in. 

Stroke of Cylinders 24 in. 

Outside Diameter of smallest Boiler Ring 46 in. 

Size of Grate . 3 ft. x 5 ft 

Number of Tubes 150 

Diameter of Tubes 2 in. 

Length of Tubes n ft. 

Square Feet of Grate surface .15 

Square Feet of Heating surface in Fire-Box 100 

Square Feet of Heating surface in Tubes 755 

Total Feet of Heating surface S55 

Exhaust Nozzles — single or double Double. 

Diameter of Nozzle 3 k 

Size of Steam Ports. 14 X 1 ~%. in. 

Size of Exhaust Ports z% in. 

Throw of Eccentrics 5 in. 

Outside Lap of Valve 13-16 in 

Inside Lap of Valve None. 

Size of Main Driving-axle Journal 7 X 7 in. 

Size of other Driving-axle Journal 7 x 7 in. 

Size of Truck-axle Journal 4% X 7 in. 

Diameter of Pump Plunger 1% in- 

Stroke of Pump Plunger „ 34 in. 

Capacity of Tank 2,000 gallons. 



Plate x. 
DIMENSIONS, WEIGHT ETC, 

OF 

TEN-WHEELED LOCOMOTIVE, 

By the Baldwin Locomotive Works, Philadelphia. 



Gauge of Road 4 ft. %% in. 

Number of Driving- Wheels 6 

Number of Front Truck- Wheels 4 

Number of Back Truck- Wheels None. 

Total Wheel Base 23 ft. 6 in. 

Distance between centres of Front and Back Driving- Wheels. . .88 in. 

Total Weight of Locomotive in working order 78,000 lbs. 

Total Weight on Driving-Wheels 58,000 lbs. 

Diameter of Driving-Wheels 54 in. 

Diameter of Truck- Wheels 26 in. 

Diameter of Cylinders 18 in. 

Stroke of Cylinders , 24 in. 

Outside Diameter of smallest Boiler Ring 50 in. 

Size of Grate 60 X 34^ in. 

Number of Tubes 152 

Diameter of Tubes 2 in. 

Length of Tubes 12 ft. 9 in. 

Square Feet of Grate surface 14-37 

Square Feet of Heating surface in Fire-Box 94 

Square Feet of Heating surface in Tubes 1014 

Total Feet of Heating surface .1108 

Exhaust Nozzles • — single or double Double. 

Diameter of Nozzle 3 to 3% in. 

Size of Steam Ports x% X 16 in. 

Size of Exhaust Ports 2% X 16 in. 

Throw of Eccentrics 5 % > n - 

Outside Lap of Valve % in. 

Inside Lap of Valve 1-32 in. 

Size of Main Driving-axle Journal ; 7 in. dia. X 8 in. 

Size of other Driving-axle Journal 7 in. dia. X 8 in. 

Size of Truck-axle Journal 4 j£ X 7% i°- 

Diameter of Pump Plunger 2 in. 

Stroke of Pump Plunger 24 in. 

Capacity of Tank * 2,200 gallons. 



565 




566 



Plate xi. 



DIMENSIONS, WEIGHT, ETC., 

OF 

"MOGUL" LOCOMOTIVE, 
By the Baldwin Locomotive Works, Philadelphia. 



Gauge of Road 4 ft. 8 y z in. 

Number of Driving-Wheels 6 

Number of Front Truck-Wheels 2 

Number of Back Truck- Wheels None. 

Total Wheel Base 22 ft. 8 in. 

Distance between centres of Front and Back Driving-Wheels. .96 in. 

Total Weight of Locomotive in working order 77 000 lbs. 

Total Weight on Driving-Wheels 66,000 lbs. 

Diameter of Driving-Wheels 52 in. 

Diameter of Truck- Wheels 30 in. 

Diameter of Cylinders , 18 in. 

Stroke of Cylinders 24 in. 

Outside Diameter of smallest Boiler Ring 50 in. 

Size of Grate 66 X 34^ in. 

Number of Tubes 161 

Diameter of Tubes 2 in. 

Length of Tubes n ft. 3 in. 

Sqaare Feet of Grate surface 16 

Square Feet of Heating surface in Fire-Box 102 . 7 

Square Feet of Heating surface in Tubes 948 

Total Feet of Heating surface. 1051 

Exhaust Nozzles — single or double Double. 

Diameter of Nozzle 3 to 3^ in. 

Size of Steam Ports 1 ~% X 16 in. 

Size of Exhaust Ports 2^£ X 16 in. 

Throw of Eccentrics $% in - 

Outside Lap of Valve ^in. 

Inside Lap of Valve 1-32 in. 

Size of Main Driving-axle Journal 7 in. dia. X 8 in. 

Size of other Driving-axle Journal .7 iH. dia. X 8 in. 

Size of Truck-axle Journal 5 in. dia. X 8 in. 

Diameter of Pump Plunger 2 in. 

Stroke of Pump Plunger 24 in. 

Capacity of Tank 2,200 gallons. 





(3k 


"MOGUL" LOCOMOTIVE, 

BY THE BALDWIN LOCOMOTIVE WORKS, PHILADELPHIA. 
Scale, % in. = l ft. 


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568 



Plate xn. 



DIMENSIONS, WEIGHT, ETC., 

OF 

"CONSOLIDATION" LOCOMOTIVE, 

BY THE 

Danfortm Locomotive and Machine Co., Paterson, N, J. 



Gauge of Road 4 ft. 8% in. 

Number of Driving- Wheels 8 

Number of Front Truck-Wheels 2 

Number of Back Truck-Wheels None. 

Total Wheel Base 23 ft. 2 in. 

Distance between centres of Front and Back Driving- 

Wheels 15 ft. 7 in. 

Total Weight of Locomotive in working order 9^550 lbs. 

Total Weight on Driving- Wheels 86,430 lbs. 

Diameter of Driving-Wheels 4 ft. 2 in. 

Diameter of Truck-Wheels 2 ft. 7 in. 

Diameter of Cylinders 20 in. 

Stroke of Cylinders 24 in. 

Outside Diameter of smallest Boiler Ring 4 ft. 2 in. 

Size of Grate 120 x 34K in ' 

Number of Tubes 165 

Diameter of Tubes 2% in. 

Length of Tubes 13 ft. 9% in. 

Square Feet of Grate surface 29 

Square Feet of Heating surface in Fire-Box 139 

Square Feet of Heating surface in Tubes 137° 

Total Feet of Heating surface 1509 

Exhaust Nozzles — single or double Double 

Diameter of Nozzle 2% ' n - 

Size of Steam Ports 1% X 15^ in. 

Size of Exhaust Ports 2^ X 15% in. 

Throw of Eccentrics 5^ in. 

Outside Lap of Valve $/% in. 

Inside Lap of Valve None. 

Size of Main Driving-axle Journal 6% in. 

Size of other Driving-axle Journal. 6% in. 

Size of Truck-axle Journal 5 in. 

Diameter of Pump Plunger 2 J^ in. 

Stroke of Pump Plunger 24 in. 

Capacity of Tank 2,400 gallons. 



568 




no 



Plate xin. 
DIMENSIONS, WEIGHT, ETC., 

OF 

DOUBLE-END TANK LOCOMOTIVE, 

BY THE 

Rogers Locomotive and Machine Works, Paterson, N. J. 



Gauge of Road 4 ft. 8^ in. 

Number of Driving- Wheels 6 

Number of Front Truck- Wheels 2 

Number of Back Truck- Wheels 2 

Total Wheel Base 24 ft. 7% in. 

Distance between centres of Front and Back Driving- Wheels. .12 ft. 

Total Weight of Locomotive in working order 84,000 lbs. 

Total Weight on Driving- Wheels 68,000 lbs. 

Diameter of Driving- Wheels 40^ in. 

Diameter of Truck- Wheels 26 in. 

Diameter of Cylinders 15 in. 

Stroke of Cylinders 20 in. 

Outside Diameter of smallest Boiler Ring 46^ in. 

Size of Grate 34 X 48 in. 

Number of Tubes 132 

Diameter of Tubes 2 in. 

Length of Tubes 9 ft 9 ~% in. 

Square Feet of Grate surface 11. 7 

Square Feet of Heating surface in Fire-Box 67 

Square Feet of Keating surface in Tubes 608 

Total Feet of Heating surface 675 

Exhaust Nozzles — single or double Double. 

Diameter of Nozzle „ 2)/% to 2% in. 

Size of Steam Ports 13% X 1 3-16 in. 

Size of Exhaust Ports 13% X 2 7-16 in. 

Throw of Eccentrics 4% in. 

Outside Lap of Valve % X 1-64 in. 

Inside Lap of Valve 1-16 in. 

Size of Main Driving-axle Journal 6 X 7% in. 

Size of other Driving-axle Journal 6 X J% in. 

Size of Truck-axle Journal 4% X 8 in. 

Diameter of Pump Plunger r% in. 

Stroke of Pump Plunger 20 in. 

Capacity of Tank. . . . = 1,600 gallons. 





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572 



Plate xrv. 



DIMENSIONS, WEIGHT, ETC., 

OF 

DOUBLE-END TANK LOCOMOTIVE. 

BY THE 

Rogers Locomotive and Machine Works, Paterson, N. J. 



Gauge of Road 4 ft Zy 2 in. 

Number of Driving- Wheels 4 

Number of Front Truck- Wheels 2 

Number of back Truck-Wheels 4 

Total Wheel Base 25 ft. 8 % in. 

Distance between centres of Front and Back Driving- Wheels . 6 ft 6 in. 

Total Weight of Locomotive in working order 75>ooo lbs. 

Total Weight on Driving- Wheels 40,000 lbs. 

Diameter of Driving- Wheels 48% in. 

Diameter of Truck- Wheels 30 and 26 in. 

Diameter of Cylinders 15 in. 

Stroke of Cylinders 22 in. 

Outside Diameter of smallest Boiler Ring 43% in. 

Size of Grate 34 X 50 in. 

Number of Tubes 139 

Diameter of Tubes 2 in. 

Length of Tubes 8 ft. io 1 ^ in. 

Square Feet of Grate surface 11 . 84 

Square Feet of Heating surface in FIre-Box 82 

Square Feet of Heating surface in Tubes 711 

Total Feet of Hearing surface 793 

Exhaust Nozzles — single or double Double. 

Diameter of Nozzle 2^ to 2^3 in. 

Size of Steam Ports 13^ X 1 3-16 in. 

Size of Exhaust Ports 13% X 2 7-16 in. 

Throw ef Eccentrics 4^ in. 

Outside Lap of Valve % X 1-64 in. 

Inside Lap of Valve 1-16 in. 

Size of Main Driving-axle Journal 6 X 7% in. 

Size of other Driving-axle Journal 6 X 7% in. 

Size of Truck-axle Journal 4% X 7% in.' 

Diameter of Pump Plunger 1% in. 

Stroke of Pump Plunger 22 in. 

Capacity of Tank i,coo gallons. 

t Above is the Front Truck-axle Journal That of the Back Truck- 
axle is 4% x 7% in. 



§78 



I 




574 



Plate xv. 



DIMENSIONS, WEIGHT, ETC., 

OF 

IMPROVED TANK LOCOMOTIVE, 

DESIGNED BY 

M. N. Forney, 73 Broadway, New York. 



L_ 



Gauge of Road 4 ft. 8% in. 

Number of Driving-Wheels 4 

Number of Front Truck- Wheels 4 

Number of Back Truck- Wheels None. 

Total Wheel Base 20 ft. 9 in. 

Distance between centres of Front and Back Driving- 
Wheels 6 ft. 8 in. 

Total Weight of Locomotive in working order 6c,ooo lbs. 

Total Weight on Driving-Wheels 44,000 lbs. 

Diameter of Driving-Wheels 50 in. 

Diameter of Truck- Wheels 26 in. 

Diameter of Cylinders 14 in. 

Stroke of Cylinders .20 in. 

Outside Diameter of smallest Boiler Ring 46 in. 

Size of Grate 54 X 36^ in. 

Number of Tubes 139 

Diameter of Tubes 2 in. 

Length of Tubes 10 ft. 1 % in, 

Square Feet of Grate surface 14 

Square Feet of Heating surface in Fire-Box 78 

Square Feet of Heating s'irface in Tubes 734 

Total Feet of Heating surface 812 

Exhaust Nozzles — single or double Double. 

Diameter of Nozzle 2% in. 

Size of Steam Ports. 12 X 1 J^ in. 

Size of Exhaust Ports 12 X 2% in. 

Throw of Eccentrics 5 in. 

Outside Lap of Valve ^ in. 

Inside Lap of Valve 1-32 in. 

Size of M:.in Driving-r::le Journal 6 X 7 in. 

Size of other Driving-axle Journal 6 X 7 in. 

Size of Truck-axle Journal 2% X 7 in. 

Diameter of Pump Plunger 4 in. 

Stroke of Pump Plunger 5 in. 

Capacity of Tank 1,500 gallons. 



576 



Plate xvt. 



DIMENSIONS, WEIGHT, ETC, 

OF 

Double-Truck Narrow-Gauge Tank Locomotive, 

By the Mason Machine Works, Taunton, Mass. 



Gauge of Road 3 ft. 

Number of Driving-Wheels 4 

Number of Front Truck- Wheels 4 

Number of Back Truck- Wheels 4 

Total Wheel Base 19 ft. 6 in. 

Distance between centres of Front and Back Driving-Wheels 5 ft. 

Total Weight of Locomotive in working order 

Total Weight on Driving-Wheels 24,000 lbs. 

Diameter of Driving-Wheels 2 ft. 9 in. 

Diameter of Truck-Wheels 2 ft. 6 in. 

Diameter of Cylinders 10 in. 

Stroke of Cylinders 1 ft. 3 in. 

Outside Diameter of smallest Boiler Ring 3 ft. 

Size of Grate 41^ X 31 in. 

Number of Tubes 81 

Diameter of Tubes 2 in. 

Length of Tubes 8 ft. 2 in. 

Square Feet of Grate surface 8.93 

Square Feet of Heating surface in Fire-Box 56 

Square Feet of Heating surface in Tubes 346 

Total Feet of Heating surface 402 

Exhaust Nozzles — single or double Single. 

Diameter of Nozzle 2^ in. 

Size of Steam Ports 9% X i l /& in. 

Size of Exhaust Ports 9^ x 2^ in. 

Throw ©f Eccentrics 3% in. 

Outside Lap of Valve ^ in. 

Inside Lap of Valve 1-16 

Size of Main Driving-axle Journal 5 x 7 in. 

Size of other Driving-axle Journal 

Size of Truck-axle Journal. .". 2% X &% m - 

Diameter of Pump Plunger 

Stroke of Pump Plunger 

Capacity of Tank 3oo gallons. 



578 



Plate xvii. 



DIMENSIONS, WEIGHT, ETC., 

OF 

DOUBLE-TRUCK TANK FREIGHT LOCOMOTIVE 

By the Mason Machine Works, Taunton, Mass. 



Gauge of Road , . . .4 ft. 8% in. 

Number of Driving- Wheels 6 

Number of Front Truck- Wheels ..... .6 

Number of Back Truck- Wheels 6 

Total Wheel Base 31 ft. 

Distance between centres of Front and Back Driving-Wheels 8 ft. 

Total Weight of Locomotive in working order 

Total Weight on Driving-Wheels 66,oco lbs. 

Diameter of Driving-Wheels 3 ft. 6 in. 

Diameter of Truck- Wheels 2 ft. 6 in. 

Diameter of Cylinders 1 ft. 4 in. 

Stroke of Cylinders 2 ft. 

Outside Diameter of smallest Boiler Ring 4 ft. 

Size of Grate 66 X 48-% in. 

Number of Tubes 154 

Diameter of Tubes 2 in. 

Length of Tubes 11 ft. 6 i.i. 

Square Feet of Grate surface 22.17 

Square Feet of Heating surface in Fire-Box 126 

Square Feet of Hearing surface in Tubes 927 

Total Feet of Hearing surface 1053 

Exhaust Nozzles — single or double Tingle. 

Diameter of Nozzle Variable. 

Size of Steam Ports 15 x x% in. 

Size of Exhaust Ports 15 X 2^ in. 

Throw of Eccentrics 8 in.* 

Outside Lap of Valve %in. 

Inside Lap of Valve 1-16 in. 

Size of Main Driving-axle Journal 6% X 10 in. 

Size of other Driving-axle Journal 

Size of Truck-axle Journal 4 x 8 in. 

Diameter of Pump Plunger 

Stroke of Pump Plunger 

Capacity of Tank 2,530 gallons. 

* This engine has Walschacrt's valve gear, which is worked 
by a crank of 8 inches throw. 




, 



580 



Plate xviii. 



DIMENSIONS, WEIGHT, ETC., 

OF 

DOUBLE-END LOCOMOTIVE, 

By the Grant Locomotive Works, Paterson, N. J. 



Gauge of Road 4 ft. 8*4 in. 

Number of Driving- Wheels , 4 

N umber of Front Truck- Wheels 2 

Number of Back Truck-Wheels 2 

Total Wheel Base 19 ft. 9 in. 

Distance between centres of Front and Back Driving- Wheels 7 ft 

Total Weight oi" Locomotive in working order 52,000 lbs. 

Total Weight on Driving- Wheels 42,000 rbs. 

Diameter of Driving- Wheels 56 in. 

Diameter of Truck- Wheels 28 in. 

Diameter of Cylinders 14 in. 

Stroke of Cylinders 22 in. 

Outside Diameter of smallest Boiler Ring 42 in. 

Size of Grate 73 x 34 in. 

Number of Tubes 124 

Diameter of Tubes 2 in. 

Length of Tubes 7 ft 10 in. 

Square Feet of Grate surface 16. 5 

Square Feet of Heating surface in Fire-Box 80.8 

Square Feet of Heating surface in Tubes 468 ,5 

Total Fee', of Heating surface 549 . 3 

Exhaust Nozzles — single or double Double. 

Diameter of Nozzle 2 % to 3% in. 

Size of Steam Ports 14 X 1% in. 

Size of Exhaust Ports 14 X 2 % in. 

Throw of Eccentrics 5 in. 

Outside Lap of Valve % in. 

Inside Lap of Valve None. 

Size of Main Driving-axle Journal 6 dia. X -j% in. 

Size of other Driving-axle Journal 6 dia. x 7^ in. 

Size of Truck-axle Journal $% dia. X 8 in. 

Diameter of Pump Plunger 3^ in. 

Stroke of Pump Plunger S in- 
capacity of Tank 1,600 gallons. 



582 



Plate xrx. 
DIMENSIONS, WEIGHT, ETC., 

OF 

LOCOMOTIVE FOR THE N. Y. ELEVATED R. R. 

Designed by D. W. Wyman, Superintendent. 

Gauge of Road .4 ft. 10 in. 

Number of Driving- Wheels 4 

Number of Front Truck-Wheels None. 

Number of Bac 1 -: Truck- Wheels None. 

Total Wheel Base 5 ft. 

Distance between centres of Fron and Back Driving- Wheels 5 ft 

Total Weight of Locomotive in working order 8,000 lbs. 

Total Weight on Driving-Wheels 8,000 lbs. 

Diameter of Driving- Wheels 30 in. 

Diameter of Truck- Wheels None. 

Diameter of Cylinders 7 in. 

Stroke of Cylinders 10 in. 

Outside Diameter of smallest Boiler Ring 28 in. 

Size of Grate 28 X 28 in. 

Number of Tubes 14c 

Diameter of Tubes 1 % in. 

Length of Tubes 3 ft. 

Square Feet of Grate surface 5% ft 

Square Feet of Heating surface in Fire-Box 25 ft 

Square Feet of Heating surface in Tubes 126 ft 

Total Feet of Heating surface 151 ft. 

Exhaust Nozzles — single or double Double. 

Diameter of Nozzle 2 in. 

Size of Steam Ports 6 X y % in. 

Size of Exhaust Ports 6 X 2 in. 

Throw of Eccentrics 2^ in. 

Outside Lap of Valve % in. 

Inside Lap of Valve 1-32 in. 

Diameter of Main Driving-axle Journal 3 in. 

Size of other Driving-axle Journal 

Size of Truck-axle Journal 

Diameter of Pump Plunger 1% in. 

Stroke of Pump Plunger 10 in. 

Capacity of Tank 109 gallons. 



583 




Appendix 1. 



585 





PROPERTIES OF SATURATED 


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] 


L97.8 


1173.7 


.0289 


2157 


12 


S 


102.0 


1175.0 


.0314 


1986 


13 


e 


505.9 


1176.2 


.0338 


1842 


14 


i 


509.6 


1177.3 


.0362 


1720 


14.7 


"o. i 


512.0 


1178.1 


.0380 


1612 


15 


.3 S 


513.1 


1178.4 


.0387 


1610 


16 


1.3 1 


516.3 


1179.4 


.0411 


1515 


17 


2.3 5 


519.6 


1180.3 


.0435 


1431 


13 


3.3 5 


522.4 


118L2 


.0459 


1357 


19 


4.3 5 


525.3 


1182.1 


.0483 


1290 


20 


5.3 \ 


528.0 


1182.9 


.0507 


1229 


21 


6.3 5 


530.6 


1183.7 


.0531 


1174 


22 


7.3 S 


533.1 


1184.5 


.0555 


1123 


23 


8.3 \ 


535.5 


1185.2 


.0580 


1075 


24 


9.3 5 


537.8 


1185.9 


.0601 


1036 


25 


10.3 \ 


540.1 


1186.6 


.0625 


996 


26 


11.3 5 


242.3 


1187.3 


.0650 


958 


27 


12.3 5 


244.4 


1187.8 


.0673 


926 


28 


13.3 i 


246.4 


1188.4 


.0696 


895 


29 


14.3 J 


248.4 


1189.1 


.0719 


866 


30 


15.3 i 


250.4 


1189.8 


.0743 


838 


31 


16.3 


252.2 


1190.4 


.0766 


813 


32 


17.3 


254.1 


1190.9 


.0789 


789 


33 


18.3 


255.9 


1191.5 


.0812 


767 


34 


19.3 


257.6 


1192.0 


.0835 


746 


35 


20.3 


259.3 


1192.5 


.0858 


726 


36 


21.3 


260.9 


1193.0 


.0881 


707 


37. 


22.3 


262.6 


1193.5 


.0905 


688 



586 



Appendix I. 



: 


PROPERTIES OF SATTRATED STEAM Costdtuid. 


r =-" Z 




-r. 

- - z 


«?! 


_.s 


< a | 

EP ~ - 

I|l 

= 11 

■ S *"• 

© _, 

: - x 

: --■ 


- X 

X = 

- r 

— - 
a 

= r 
■ c 

i I 


» _ - 

-. — 

N 

■ : 


-. z — 

: * =■ 

: o «*■ 
: z ,= 
■ S 1 ^ 


i - 

-I 

. o 

• ^ 


< ■ s £ 

■ g 2 B 

• s 2 » 


• a i- 
: =-p 


'■ ? 
■ - 


H 


• EC " 


; tf 


. — — - 


Lb. 


Lb. 


Deg. 


Deg. 


Lb. 




38 


23.3 261.2 


1194.0 


.0929 


571 


39 


24.3 265.8 


1194.5 


.0952 


555 


40 


25.3 267.3 


1191.9 


.0974 


640 


41 


26.3 2 


168.7 


1195.1 


.0996 


625 


42 


27.3 S 


170.2 


1195.8 


.1020 


611 


43 


28.3 5 


171.6 


1196.2 


.1042 


598 


44 


29.3 5 


173.0 


1196.6 


.1065 


585 


45 


30.3 I 


574.4 


1197.1 


.1089 


572 


46 


31.3 5 


175.8 


1197.5 


.1111 


561 


47 


32.3 S 


177.1 


1197.9 


.1133 


550 


48 


33.3 I 


178.4 


1198.3 


.1156 


539 


49 


31.3 5 


179.7 


1198.7 


.1179 


529 


50 


35.3 i 


181.0 


1199.1 


.1202 


518 


51 


36.3 5 


182.3 


1199.5 


.1221 


509 


52 


37.3 : 


183.5 


1199.9 


.1216 


500 


53 


38.3 S 


>84.7 


12U0.3 


.1269 


491 


54 


39.3 5 


185.9 


1200.6 


.1291 


482 


55 


40.3 \ 


187.1 


1201.0 


.1314 


474 


56 


41.3 : : 


188.2 


1201.3 


.1336 


466 


57 


42.3 S 


189.3 


1201.7 


.1361 


45S 


58 


43.3 : 


190.4 


1202.0 


.1380 


451 


59 


44.3 : 


191.6 


1202.4 


.1103 


444 


60 


45.3 : 


192.7 


1202.7 


.1425 


437 


61 


46. 3 I 


193.8 


1203.1 


.1447 


430 


62 


47.3 


.94.8 


1203.4 


.1469 


424 


63 


48.3 5 


195.9 


1203.7 , 


.1193 


417 


64 


49.3 5 


196.9 


1204.0 


.1516 


411 


65 


50.3 S 


198.0 


1204.3 


.1538 


405 


66 


51.3 5 


199.0 


1204.6 


.1560 


399 


67 


52.3 £ 


500.0 


1204.9 


.1583 


393 


68 


53.3 I 


500.9 


1205.2 


.1605 


388 


69 


51.3 £ 


501.9 


1205.5 


.1627 


383 


70 


55.3 { 


502.9 


1205.8 


.1648 


373 


71 


56.3 £ 


503.9 


1206.1 


.1670 


373 


72 


57.3 J 


504.8 


1206.3 


.1692 


368 


73 


58.3 { 


505.7 


1206.6 


,1711 


363 


71 


59.3 J 


506.6 


1206.9 


.1736 


359 


75 


1 . 60.3 l 


507.5 


1207.2 


.1759 


353 



Appendix 1. 



587 



PROPERTIES OF SATURATED STEAM— Continued. 


i 


S B 3 

*«> 
&« 

»*2 


?cd 
3 to 

iS 

3- CD 
■B 

o 
<1 

CD 


3Sg 
? s. 

/> No- 

I! 

CD'S 


ill 

: 2,0 
: get 


§2. 

oi 

£^ 
8 o 

Bg 

• CD 

: a 

• Pi 


Relative volume of 
steam compared w 
the water from wh 
it was raised 




B 1 ? 


CD 


Da Pi 

i CD 


• i BO 


•' 2! 

• 5' 


. p^trcD 


Lb. 


Lb. 


Deg. 


Deg. 


Lb. 




76 ( 


$1.3 I 


508.4 


1207.4 


.1782 


349 


77 ( 


$2.3 I 


$09.3 


1207.7 


.1804 


345 


78 ( 


>3.3 ( 


$10.2 


1208.0 


.1826 


341 


79 ( 


$4.3 J 


$11.1 


1208.3 


.1848 


337 


80 ( 


$5.3 i 


$12.0 


1208.5 


.1869 


333 


81 ( 


$6.3 I 


$12.8 


1208.8 


.1891 


329 


82 ( 


J7.3 i 


$13.6 


1209.1 


.1913 


325 


83 ( 


$8.3 < 


$14.5 


1209.4 


.1935 


321 


84 ( 


59.3 J 


$15.3 


1209.6 


.1957 


318 


85 


r0.3 I 


$16.1 


1209.9 


.1980 


314 


86 


7 1.3 i 


$16.9 


1210.1 


.2002 


311 


87 r i 


? 2.3 i 


$17.8 


1210.4 


.2024 


308 


88 ■; 


'3.3 ^ 


$18.6 


1210.6 


.2044 


305 


89 -; 


'4.3 [- 


$19.4 


1210.9 


.2067 


301 


90 "3 


r 5.3 I 


$20.2 


1211.1 


.2089 


298 


91 ■; 


'6.3 ? 


$21.0 


1211.3 


.2111 


295 


92 


7.3 c 


$21.7 


1211.5 


.2133 


292 | 


93 


'8.3 £ 


$22.5 


1211.8 


.2155 


289 


94 1 


r 9.3 < 


$23.3 


1212.0 


.2176 


286 


95 £ 


$0.3 i 


$24.1 


1212.3 


.2198 


283 


96 e 


$1.3 S 


$24.8 


1212.5 


.2219 


281 


97 £ 


$2.3 I 


$25.6 


1212.8 


.2241 


278 


98 6 


3.3 ? 


$26.3 


1213.0 


.2263 


275 


99 £ 


4.3 £ 


$27.1 


1213.2 


.2285 


272 


100 t 


5.3 I 


$27.9 


1213.4 


.2307 


270 


101 £ 


>6.3 £ 


$28.5 


1213.6 


.2329 


267 


102 6 


7.3 J 


$29.1 


1213.8 


.2351 


265 ' 


103 £ 


8.3 J 


$29.9 


1214.0 


.2373 


262 ) 


104 S 


$9.3 £ 


$30.6 


1214.2 


.2393 


260 | 


105 J 


10.3 i 


$31.3 


1214.4 


.2414 


257 I 


106 i 


H.3 < 


$31.9 


1214.6 


.2435 


255 | 


107 £ 


2.3 i 


$32.6 


1214.8 


.2456 


253 ! 


108 i 


3.3 c 


$33.3 


1215.0 


.2477 


251 ! 


109 c 


14.3 J 


$34.0 


1215.3 


.2499 


249 


110 c 


15.3 I 


$34.6 


1215.5 


.2521 


247 i 


111 c 


6.3 J 


$35.3 


1215.7 


.2543 


245 1 


112 £ 


7.3 i 


$36.0 


1215.9 


.2564 


243 I 


113 i 


8.3 c 


$36.7 


1216.1 


.2586 


241 1 


.. . 













588 



Appendix I. 



PROPERTIES OF SATURATED STEAM— Continued. 


£5» 


p£ 


1 2. 
s» a> 


-•o r*- 


2* 

si- 

og 


sss-c? 
3 ® p p 

w 1 c 5 

1-5 S-C5 CD 
P CD O < 


: S* 
: 2.2 

CD 

'. C 5 ""* 


CD 
'** 

• o 


CD CD 

* 


as - 
5^ 


Si 

. CD 

: g 


.- o » S 
. a i-s S 

. O CD CD 


• O CD 

: B*? 


: 6= 

• CD 


cp £ 


CD CD 

«?2 


: | 

• 5' 


. (3* F CD 


Lb. 


Lb. 


Deg. 


Deg. 


Lb. 




114 


99.3 r c 


$37.4 1 


216.3 


.2607 


239 


115 


100.3 J 


$38.0 1 


216.5 


.2628 


237 


116 


101.3 i 


$38.6 1 


216.7 


.2649 


235 


, 117 


102.3 J 


$39.3 1 


216.9 


.2674 


233 


118 


103.3 I 


$39.9 1 


217.1 


.2696 


231 


119 


104.3 : 


$40.5 1 


217.3 


.2738 


229 


120 


105.3 : 


$41.1 1 


217 .4 


.2759 


227 


121 


106.3 : 


$41.8 1 


217.6 


.2780 


225 


122 


107.3 : 


$42.4 1 


217.8 


.2801 


224 


123 


108.3 : 


$43.0 1 


218.0 


.2822 


222 


124 


109.3 


343.6 1 


218.2 


.2845 


221 


125 


110.3 


344.2 1 


218.4 


.2867 


219 


126 


111.3 


344.8 1 


218.6 


.2889 


217 


127 


112.3 


345.4 1 


218.8 


.2911 


215 


128 


113.3 


346.0 1 


218.9 


.2933 


214 


129 


114.3 


346.6 1 


219.1 


.2955 


212 


130 


115.3 


347.2 1 


219.3 


.2977 


211 


131 


116.3 


347.8 1 


219.5 


.2999 


209 


132 


117.3 


348.3 1 


219.6 


.3020 


208 


133 


118.3 


348.9 1 


219.8 


.3040 


206 


134 


119.3 


349.5 1 


220.0 


.3060 


205 


135 


120.3 


350.1 1 


220.2 


.3080 


203 


136 


121.3 


350.6 1 


220.3 


.3101 


202 


137 


122.3 


351.2 1 


220.5 


.3121 


200 


138 


123.3 


351.8 1 


220.7 


.3142 


199 


] 139 


124.3 


352.4 1 


220.9 


.3162 


198 


i 140 


125.3 


352.9 1 


221.0 


.3184 


197 


141 


126.3 


353.5 1 


221.2 


.3206 


195 


i 142 


127.3 


354.0 ] 


221.4 


.3228 


194 


143 


128.3 


354.5 3 


221.6 


.3250 


193 


144 


129.3 


355.0 ] 


221.7 


.3273 


192 


145 


130.3 


355.6 ] 


221.9 


.3294 


190 


146 


131.3 


356.1 ] 


.222.0 


.3315 


189 


147 


132.3 


356.7 1 


222.2 


.3336 


188 


148 


133.3 


357.2 1 


.222.3 


.3357 


187 


149 


134.3 


357.8 ] 


222.5 


.3377 


186 


150 


135.3 


358.3 ] 


.222.7 


.3397 


184 


155 


140.3 


361.0 1 ] 


223.5 


.3500 


179 



Appendix I, 



589 



PROPERTIES OF SATURATED STEAM— Continued. 



( 


I p g. 

< a ST 

^£ 

SB* 

3 S° a: 


Pressure above 
atmo&phere 


8 J* 

CD Irj O* 

: g.5" 

• CD»T3 
; ^0 

: 3 




Total beat in deg 
from zero of Fab 
heit 


4 

CD 

i§ 

; CD 


1 Relative volume 
steam comparud 
the water from w 
it was raised 




O DD 




: P.H" 




cd cd 


■ P 


: ZS.Z 




5 1 ? 


: g" 


■ ® 3 

1 CD 


: ?S 


• O 


. P'P'CD 


Lb. 


Lb. 


Deg. 


Deg. 


Lb. 




160 


145.3 


363.4 


1224.2 


.3607 


174 


165 


150.3 


366.0 


1224.9 


.3714 


169 


170 


155.3 


368.2 


1225.7 


.3821 


164 


175 


160.3 


370.8 


1226.4 


.3928 


159 


180 


165.3 


372.9 


1227.1 


.4035 


155 


185 


170.3 


375.3 


1227.8 


.4142 


15t 


190 


175.3 


377.5 


1228.5 


.4250 


148 


195 


180.3 


379.7 


1229.2 


.4357 


144 


200 


185.3 


381.7 


1229.8 


.4464 


141 


210 


195.3 


386.0 


1231.1 


.4668 


135 


220 


205.3 


389.9 


1232.3 


.4872 


129 


230 


215.3 


393.8 


1233.5 


.5072 


123 


240 


225.3 


397.5 


1234.6 


.5270 


119 


250 


235.3 


401.1 


1235.7 


.5471 


114 


260 


245.3 


404.5 


1236.8 


.5670 


110 


270 


255.3 


407.9 


1237.8 


.5871 


106 


280 


265.3 


411.2 


1238.8 


.6070 


102 


290 


275.3 


414.4 


1239.8 


.6268 


99 


« 


*00 


285.3 


417.5 


1240.7 


.6469 


96 



590 



Appeiidix II. 



Table of Hyperbolic Logarithms. 



Num. 


Loga- 
rithms. 

~~. ~0099~ 


Num. 


Loga- 
rithms. 


iN'um. 



1.91 


Loga- 
rithms. 

.6471 


Num. 


Loga- 
rithms. 


1.01 


1.46 


.3784 


2.36 


.8586 


1.02 


.0198 


1.47 


.3852 


1.92 


.6523 


2.37 


.8628 


1.03 


.0295 


1.48 


.3920 


1.93 


.6575 ! 


2.38 


.8671 


1.04 


.0392 i 


1.49 


.3987 


1.94 


.6626 


2.39 


.8712 


1.05 


.0487 


1.50 


.4054 


1.95 


.6678 


2.40 


.8754 


1.06 


.0582 


1.51 


.4121 


1.96 


.6729 


2.41 


.8796 


1.07 


.0676 


1.52 


.4187 


1.97 


.6780 


2.42 


.8837 


1.08 


.0769 


1.53 


.4252 


1.98 


.6830 


2.43 


.8878 


1.09 


.0861 


1.54 


.4317 


1.99 


.6881 


2.44 


.8919 


1.10 


.0953 


1.55 


.4382 


2.00 


.6931 


2.45 


.8960 


1.11 


.1043 


1.56 


.4446 


2.01 


.6981 


2.46 


.9001 


1.12 


.1133 


1.57 


.4510 


2.02 


.7030 


2.47 


.9042 


1.13 


.1222 


1.58 


.4574 


2.03 


.7080 


2.48 


.9082 


1.14 


.1310 


1.59 


.4637 


2.04 


.7129 


2.49 


.9122 


1.15 


.1397 


1.60 


.4700 


2.05 


.7178 


2.50 


.9162 


1.16 


.1484 


1.61 


.4762 


2.06 


.7227 


2.51 


.9202 


1.17 


.1570 


1.62 


.4824 


2.07 


.7275 


2.52 


,9242 


1.18 


.1655 


1.63 


.4885 


2.08 


.7323 


2.53 


.9282 


1.19 


.1739 


1.64 


.4946 


2.09 


.7371 


2.54 


.9321 


1.20 


.1823 


1.65 


.5007 


2.10 


.7419 


2.55 


.9360 


1.21 


.1962 


1.66 


.5068 


2.11 


.7466 


2.56 


.9400 


1.22 


.1988 


1.67 


.5128 


2.12 


.7514 


2.57 


.9439 


1.23 


.2070 


1.68 


.5187 


2.13 


.7561 


2.58 


.9477 


1.24 


.2151 


1.69 


.5247 


2.14 


.7608 


2.59 


.9516 


1.25 


.2231 


1.70 


.5306 


2.15 


.7654 


2.60 


.9555 


1.26 


.2341 


1.71 


.5364 


2.16 


.7701 


2.61 


.9593 


1.27 


.2390 


1.72 


.5423 


2.17 


.7747 


2.62 


.9631 


1.28 


.2468 ! 


1.73 


.5481 


2.18 


.7793 


2.63 


.9669 


1.29 


.2546 


1.74 


.5538 


2.19 


.7839 


2.64 


.9707 


1.30 


.2623 


1.75 


.5596 


2.20 


.7884 


2.65 


.9745 


1.31 


.2700 


1.76 


.5653 


2.21 


.7929 


2.66 


.9783 


1.32 


.2776 


1.77 


.5709 


2.22 


.7975 


2.67 


.9820 


1.33 


.2851 


1.78 


.5766 


2.23 


.8021 


2.68 


.9858 


1.34 


.2926 


1.79 


.5822 


2.24 


.8064 


2.69 


.9895 


1.35 


.3001 


1.80 


.5877 


2.25 


.8109 


2.70 


.9932 


1.36 


.3074 


1.81 


.5933 


2.26 


.8153 


2.71 


.9969 


1.37 


.3148 


1.82 


.5988 


2.27 


.8197 


2.72 


1.0006 


1.38 


.3220 


1.83 


.6043 


2.28 


.8241 


2.73 


1.0043 


1.39 


.3293 


1.84 


.6097 


2.29 


.8285 


2.74 


1.0079 


1.40 


.3364 


1.85 


.6151 


2.30 


.8329 


2,75 


1.0116 


1.41 


.3435 


1.86 


.6205 


2.31 


.8372 


2.76 


1.0152 


1.42 


.3506 


1.87 


.6259 


2.32 


.8415 


2.77 


1.0188 


1.43 


.3576 


1.88 


.6312 


2.33 


.8458 


2.78 


1.0224 


1.44 


.3646 


1.89 


.6365 


2.34 


.8501 


2.79 


1.0260 


1.45 


.3715 


1.90 


.6418 


1 2.35 


.8544 


2.80 


1.0296 



Ajjpendix II 



591 



Table 


yf Hyperbolic Logarithms — Continued. 


Num. 
2.81 


Loga- 
rithms. 


Num. 


Loga- 1 
rithms. 


Num. 


Loga- 
rithms. 


Num. 
4.16 


Loga- 
rithms. 

1.4255 


1.0331 


3.26 


1.1817 


3.71 


1.3110 


2.82 


1.0367 


3.27 


1.1847 


3.72 


1.3137 


4.17 


1.4279 


2.83 


1.0402 


3.28 


1.1878 


3.73 


1.3164 


4.18 


1.4303 


2.84 


1.0138 


3.29 


1.1908 


3.74 


1.3190 


4.19 


1.4327 


2.85 


1.0473 


3.30 


1.1939 


3.75 


1.3217 


4.20 


1.4350 


2.86 


1.0508 


3.31 


1.1969 


3.76 


1.3244 


4.21 


1.4374 


2.87 


1.0543 


3.32 


1.1999 


3.77 


1.3271 


4.22 


1.4398 


2.88 


1.0577 


3.33 


1.2029 


3.78 


1.3297 


4.23 


1.4422 


2.89 


1.0612 


3.34 


1.2059 


3.79 


1.3323 


4.24 


1.4445 


2.90 


1.0647 


3.35 


1.2089 


3.80 


1.3350 


4.25 


1.4469 


2.91 


1.0681 


3.36 


1.2119 


3.81 


1.3376 


4.26 


1.4492 


1 2.92 


1.0715 


3.37 


1.2149 


3.82 


1.3402 


4.27 


1.4516 


f 2.93 


1.0750 


3.38 


1.2178 


3.83 


1.3428 


4.28 


1.4539 


2.94 


1.0784 


3.39 


1.2208 


3.84 


1.3454 


4.29 


1.4562 


2.95 


1.0818 


3.40 


1.2237 


3.85 


1.3480 


4.30 


1.4586 


2.96 


1.0851 


3.41 


1.2267 


3.86 


1.3506 


4.31 


1.4609 


2.97, 


1.0885 


3.42 


1.2296 


3.87 


1.3532 


4.32 


1.4632 


2.98 


1.0919 


3.43 


1.2325 


3.88 


1.3558 


4.33 


1.4655 


2.99 


1.0952 


3.44 


1.2354 


3.89 


1.3584 


4.34 


1.4678 


3.00 


1.0986 


3.45 


1.2387 


3.90 


1.3609 


4.35 


1.4701 


3.01 


1.1019 


3.46 


1.2412 


3.91 


1.3635 


4.36 


1.4724 


3.02 


1.1052 


3.47 


1.2441 


3.92 


1.3660 


4.37 


1.4747 


3.03 


1.1085 


3.48 


1.2470 


3.93 


1.3686 


4.38 


1.4778 


3.04 


1.1118 


3.49 


1.2499 


3.94 


1.3711 


4.39 


1.4793 


3.05 


1.1151 


3.50 


1.2527 


3.95 


1.3737 


4.40 


1.4816 


3.06 


1.1184 


3.51 


1.2556 


3.96 


1.3726 


4.41 


1.4838 


3.07 


1.1216 


3.52 


1.2584 


3.97 


1.3787 


4.42 


1.4838 


3.08 


1.1249 


3.53 


1.2612 


3.98 


1.38*2 


4.43 


1.4883 


3.09 


1.1281 


3.54 


1.2641 


3.99 


1.3&,7 


4.44 


1.4906 


3.10 


1.1314 


3.55 


1.2669 


4.00 


1.3862 


4.45 


1.4929 


3.11 


1.1346 


9.56 


1.2697 


4.01 


1.3887 


4.46 


1.4914 


3.12 


1.1378 


3.57 


1.2725 


4.02 


1.3912 


4.47 


1.4973 


3.13 


1.1410 


3.58 


1.2753 


4.03 


1.3937 


4.48 


1.4996 


3.14 


1.1442 


3.59 


1.2781 


4.04 


1.3962 


4.49 


1.5018 


3.15 


1.1474 


3.60 


1.2809 


4.05 


1.3987 


4.50 


1.5040 


3.16 


1.1505 


3.61 


1.2837 


4.06 


1.4011 


4.51 


1.5062 


3.17 


1.1537 


3.62 


1.2864 


4.07 


1.4036 


4.52 


1.5085 


3.18 


1.1568 


3.63 


1.2893 


4.08 


1.4060 


4.53 


1.5107 


3.19 


1.1600 


3.64 


1.2919 


4.09 


1.4085 


4.54 


1.5129 


3.20 


1.1631 


3.65 


1.2947 


4.10 


1.4109 


4.55 


1.515.1 


3.21 


1.1662 


3.66 


1.2974 


4.11 


1.4134 


4.56 


1.5173 


3.22 


1.1693 


3.67 


1.3001 


4.12 


1.4158 


4.57 


1.5195 


3.23 


1.1724 


3.68 


1.3029 


4.13 


1.4182 


4.58 


1.5216 


3.24 


1.1755 


3.69 


1.3056 


4.14 


1.4206 


4.59 


1.5238 


3.25 


1.1786 


3.70 


1.3083 


4.15 


1.4231 


4.60 


1.5260 



592 



Appendix II. 





Table 


of Hyperbolic Logarithms — Continued 


• 


Num. 


Loga- 
rithms. 


Num. 


Loga- 
rithms. 


Num. 


Loga- 
rithms. 


Num. 


Loga- 
rithms. 


4 61 


1.5282 


To6~ 


1.6213 


~5.i;r 


1.7065 


5 96 


1.7850 


4.62 


1.5303 


5.07 


1.6233 


5.52 


1.7083 


5.97 


1.7867 


4 63 


1.5325 


5.08 


1.6253 


5.53 


1.7101 


5.98 


1.7884 


4 64 


1.5347 


5.09 


1.6272 


5 54 


1,7119 


5 99 


1.7900 


4 65 


1.5368 


5.10 


1.6292 


5.55 


1 7137 


6.00 


17917 


4 66 


1.5390 


5 11 


1 6311 


5.56 


17155 


6.01 


1 7934 


4.67 


1.5411 


5.12 


1.6331 


5.57 


1.7173 


6 02 


17950 


4. 68 


1.5432 


5 13 


1.6351 


5 58 


17191 


6.03 


1 7967 


4.69 


1.5454 


5.14 


1.6370 


5.59 


1.7209 


6.04 


17984 


4 70 


1.5475 


5.15 


1.6389 


5.60 


1 7227 


6.05 


1.8000 


4.71 


1.5496 


5.16 


1.6409 


5 61 


1 7245 


6 06 


1.8017 


4 72 


1.5518 


5.17 


1,6428 


5.62 


1.7263 


6 07 


1.8033 


4.73 


1.5539 


5.18 


1 6448 


5.63 


1.7281 


6.08 


1.8U50 


4.74 


1.5560 


5.19 


1.6463 


5 64 


1.7298 


6.09 


1.8066 


4.75 


1.5581 


5.20 


1.6486 


5.65 


1.7316 


6 10 


1.8082 


4.76 


1.5602 


5.21 


J. 6505 


5.66 


1.7334 


6.11 


1.8099 


4.77 


1.5623 


5.22 


1.6524 


5.67 


1.7351 


6 12 


1.8115 


4.78 


1 5644 


5.23 


1.6544 


5 68 


17369 


6.13 


1.8131 


4.79 


1.5665 


5 24 


1.6563 


5 69 


1.7387 


6 14 


1.8148 


4.80 


1.5686 


5.25 


1.6582 


5 70 


1 7404 


6.15 


1.8164 


4.81 


1.5706 


5.26 


1.6601 


5.71 


1.7122 


6.16 


18180 


4 82 


1.5727 


5 27 


1.6620 


5.72 


1.7439 


6 17 


1.8196 


4.83 


1.5748 


5.28 


1 6639 


5.73 


1.7457 


6.18 


1.8213 


4.84 


1.5769 


5.29 


1 6658 


5 74 


17474 


6.19 


1.8229 


4.85 


1.5789 


5.30 


1.667? 


5 75 


1.7491 


6.20 


1.8245 


4.86 


158L0 


5.31 


1.6695 


5.76 


1.7509 


6.21 


1.8261 


4.87 


15830 


5 32 


1.6714 


5.77 


1.7526 


6.22 


1.8277 


4.88 


1.5851 


5.33 


1.6733 


5.78 


1.7544 


6.23 


1.8293 


4 89 


1.5870 


5.34 


1.6752 


5.79 


1.7561 


6 24 


1.83U9 


4.90 


1.5892 


5.35 


i.6770 


5.80 


1.7578 


6.25 


1.8325 


4 91 


1.5912 


5.36 


1.6789 


5.81 


1.7595 


6.26 


18341 


4 92 


1.5933 


5 37 


1.6808 


5.82 


17613 


6.27 


1.8357 


4.93 


1.5953 


5.38 


1.6826 


5 83 


1.7630 


6 28 


1.8373 


4.94 


1.5973 


5.39 


1.6845 


5 84 


1.7647 


6 29 


1.8389 


4.95 


1.5993 


5.40 


1.6863 


5.85 


1 7664 


6.30 


1 .84U5 


4.96 


1.6011 


5.41 


16882 


5 86 


1.7681 


6.31 


1.8421 


4 97 


1.6034 


5 42 


1.6900 


5.87 


17698 


6.32 


1.8437 


4 98 


1.6054 


5.43 


1.6919 


5.88 


17715 


6.33 


1.8453 


4 99 


1.6074 


5.44 


1.6937 


5.89 


1.7732 


6 34 


1.8468 


5.00 


1.6094 


5.45 


1.6956 


5.90 


1.7749 


6.35 


1.8484 


5.01 


1.6114 


5.46 


1.6974 


5.91 


1.7766 


6.36 


1.8500 


5.02 


1.6134 


5.47 


1.6992 


5.92 


1.7783 


6.37 


1.8515 


5.03 


1 6151 


5.48 


1.7011 


5.93 


1.7800 


6.38 


1.8531 


5 04 


1.6174 


5.49 


1.7029 


5.94 


1.7817 


6 39 


18547 


5 05 


1.6193 


5 50 


1.7047 


5.95 


:\7b33 


6.40 


1.8562 



5S4 



Appendix III. 



Steam from 212 D from 1 
of combustible matter. 



OOOtXNOQOOOX^XiMOJOOCOOI 

cdddoJodsdodoicftHOOH 



Av. weight in lbs. of un- 
burnt coke left on grate 
after each experiment. 



-*(M?ieH?!OHO!MMOOHH(SH 



Weight of clinker alone 
from 100 of coal 

Total waste in the state 
of ashes and clinker 
from 100 of coal 



HOOCOHH^HlOOW^CQO^HN 



HOOOt>Q0(MX)00O.~5X00(NO«)t> 



Pounds of steam to 1 of 
coal from 212° 



O05OOX05©O00Q0CiZ)03ClC5OC 



Earthy matter in 100 
parts . , v 



t>LO-*OtOWQO)HO^XOO(NOGOI> 



Fixed carbon 
parts 



in 100 



I 0© rA 
I OO OS 



• 00 

•o 






onoa 
















tH b-00 CO 
CO <X> OS iO 


• CM 




; 


CM CN-* l£> 

1— 1 T— 1 tH — 1 



Volatile combustible 
matter in 100 parts . . 



(M CN CO CM O CO O 

COtOlO^OfNCOlOCOOlOtDOHOCrt 
OXI>50l000HffiOL0 03(NOt>CM05C0 

doiHridioddxcooHH -hh!oj 

^tiCi->-di^T^-rH^^^cX)t>^^H^^^Tt< 



Cubic feet of space re- 
quired to stow a ton. . 



Weight per cubic foot 
by experiment 



noiomcMCSCX^ct-OHpffit-^ 

Ci^Cl>COCOWOOt-0(MlOt>!M^© 

^cdcocdio'odc^Ld^cMT-H^^cd^cdcN 

lO W lO W K5 tH ■* 1Q -^ CO CO O LP o to ICO 



«3 e3 «3 cs e3 c3 
pL| PL( Pn p., Ph Ph 



c3 c3 c3 c3 T3 



CO"3 . 

^^ : 

© CD . 

00 * a 
3S.§° 

l> > CD O -r- ^ 

c3 c3 ^ c3 rd o 
CD CD O CD CD c3 



'. ^3 ^3 'd t5 



J * 



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^S ° °^ 

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>s cd a o o 






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d £ ^ 7! ^ <D 

00|^gcHj 

lO lO C3 g Ojj 
^ ^^ d - rt 

ggoOii bl 

r^ r-J <D cd d S 






Appendix UL 



5^5 



riOMflONOCTOHHQOOHMHO • O t> 00 W 00 O W tH N 

t>WMI>0OMTH-^HH»a>TP0O»Ct» ■H©^ »OI>H-* COO 

HffilXNOOtNHIXXiCTlOOOt-lOt-CD •t*'* 50(MH l>01l>t> 

HddHciddoiQoixoiQodoici .' as* oo cs 06 cs t-^ oo t^ rH 



CO>OI>l>(NI>WOO'*OOJW10W'!fl(MHOO(MI>05t>Hl>l>05t 



^CDOOQOt>t>H005(MCOHCO(NCO'*05©'*OTTH-* 
WO^On^THOOHOOOtMW^HOQHOOHiXlOl© 

CO CM* CO CO CO tH CO CO rH° »d <X> rH CO rH 00 rtf rH CO -^JH SO CQ SO* tH CO us © -A 






oscofflOfM^oswts^o^ot-wcq^t- 

ffll0«(N050500t>OC0l>©C0OXi>(M(M 

i«5odt>oJHTiidoddos-*o5dd • cosd^ididc'odid© 

ItH i— IHH t— I rH t — I i — I • t — I rH r- I 



C-THSOrH00©LO!M© 

COOOO«DH(NHCO 



OSrH SO* 



as as as oo © as as as oo oo ad t- as oo c~ oo oo • oo t» oo j> oo so* od t> rH 



'Ol^HOWCOOOiOTtlOQOOOO^'ddCJiTtlMlOiM-^iodl^Tfld 



> t— I CO -rH 

> oo as rH 
: odrH*ad 

>rH iO id 



10 rH co rH co c~ as < 



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i rH t> as 

' as so co 

i CO CO CO 



rHlOH(N 
> 00 00 © O 

i co" t> t>* so* 

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I lO © CO CO LO rH -— llOlOlOrHlO©rHOSI>-rHlOrH M 00 00000©0 

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egg* 

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sh 

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5I& 

PhOA 



596 



Appendix IV. 







cB 


T 


00 


71 


— 


O 


OS 


X 


t- 


CO 


l7 


l7 


^ 


os 




•jnoq jad saiiui 02, 


— 
CO 


DO 


X 

00 


1 — 


71 

— 


u7 


l7 

— 


— 


05 

— 


^i 


OQ 

l7 


u7 


--7 


CO 
CO 




c 


X 


c- 


CO 


u7 


— 


CC 


71 


rH 





05 


OS 


L7 


CO 




•jnoq jad safini 09 


71 


X 
71 



oo 


C7 


— 
77 


t- 


X 

oa 




71 


-r 


kO 


OS 


77 
kQ 


CO 




CO 


■<* 


00 


71 


_ 


O 


7: 


X 


l> 


CO 


id 


u7 


t-H 


OS 




•jnoq jad S8[tni 00 


3 


CM 

71 


— 

71 


71 


X 

71 


— 
CO 


:r 


C7 
DO 




t- 

00 


CO 

77 


77 

-- 




OS 




X 


CO 


lO 


-* 


CO 


<M 


_ 


O 


~ 


X 


t^ 


kO 


77 


n 


* 


•jnoq jad sajiai Qf 


1 — 


os 


1 — 1 
71 


71 


L7 

71 


71 


05 


co 


71 
00 


oo 


"-7 

:7 


O 








































03 


1 — 


O 


r-. 


X 


t> 


-.7 


iO 


T 


CO 


71 


O 


X 


CO 


J? 

6 


•jnoq jad sa[ica ot 




ir- 


- 


71 


71 
71 


x* 

7J 


CO 
71 


X 

71 


O 
05 


71 

CO 


OQ 


X 

CO 


— 


— 

"CF 




rH 


es 


X 


r^ 


:7 


l7 


rH 


77 


71 


,_ 


a 


GO 


■— 


^ 




•jnoq iad sanai eg 


C7 




:7 


X 


ri 


71 

71 


71 


CO 
71 


X 

71 




00 


71 

77 


L7 

C7 


77 






IN 


— 


ce 


X 


i-- 


CC 


kO 


— 


CO 


71 


T~ 


05 


l> 


*© 




•xaoq J9d sajnn 08 


I-H 


00 

iH 


r— 


so 


X 

1 — 1 


8 


71 
71 


7l 


--7 


X 

71 


77 


77 
CO 


77 


O 




CO 


T 


^H 


cn 


,_ 





05 


X 


c^ 


CO 


O 


OQ 


_ 


os 


CO 


•jnoq jad safinr 03 


- 


1 — 


ea 


l7 


T— 


05 


i-H 

71 


71 
71 


— 
71 


CC 

71 


X 

71 


71 
77 


CO 

CC 


OS 
CO 




OQ 


_ 


c 


05 


X 


L^ 


CO 


iQ 


— 


77 


71 


O 


CO 


CO 




jnoq jad sanxu 03 


X 


O 
rH 


71 

1 — 1 


00 

— 


u7 


I- 

1 — 


OS 


71 


CO 

71 


71 


71 


— 
CO 


— 

CO 


CO 
CO 






























c 




DO 


— 


O 


n 


X 


t- 


CO 


l7 


-* 


03 


71 


O 


X 


CO 


<*> 


•jnoq jad sanni gi 


C- 


OS 


~ 


71 

T— 1 


«* 


CO 


X 

1 — 


71 


71 
71 


S 


7^ 


C7 
C7 


CO 

CO 


CO 




co 


-t 


CO 


71 


_ 


O 


OS 


X 


L— 


CO 


O 


C7 


„ 


OS 


s 
e 

1 


•inoq jad sa[ini oi 


CO 


X 





71 

r- 


-r 


CD 

r— 


c- 


35 
1 — 


71 


C7 

71 


kQ 

71 


?i 


C7 
M 


CO 
CO 


•jnoq 
jad sajroi 9 jo 
a;^j vs ' 'no; jad 


CO 


OS 
l> 


CO 
05 


— 


CO 

06 

1 — 


kfl 


— 




71 

71 


77 

71 


O 

kd 

71 


X 
X 
71 


CO 

71 

77 


CO 
CO 


►2 


•sqx 'aon'Bisisaj v^io j, 




























•nrej;jo(-sqt 
000'z) uoj jad -eqi 
m auoiB ^uaosB 




X 


00 


-.7 


u7 


x* 
OS 


co 
1— 1 


71 

CO 

•— 


kd 


q 

1 — 


05 

X 


71 
71 


CD 

71 


co 


CO 




oi anp aouBjsisaa 
































•an;ni jad ;aaj 
'q.uaipi3J2 jo ast^j 


































c 





77 

T— 


i-7 

1 — 1 


C^ 


■ 7 
71 




DO 


OQ 







77 
i-7 


s 


O 


SB 



Appendix IV. 



597 



tO 


Tf) 


Ol 


o 


oo 


CO 


-<* 


CN 


OS 


IT- 


LO 


CO 


^ 


CO 


IT- 


-* 


Ol 


© 


X 


CO 


^H 


CN 


X 


oo 


CO 


o 


00 


l~- 


1—1 


>o 


■.TO 


CN 


CO 


© 


-H 


h- 


1 — 1 


kO 


OS 


Ol 


CO 


© 


■<* 


CO 


CO 


t- 


t- 


CO 


CO 


00 


OS 


os 


OS 


o 


o 


I— 1 


T— 1 


1 — 1 


Ol 


Ol 


Ol 


CO 


CO 


■* 


tH 


tH 


o 


oo 


CO 


-* 


Ol 


o 


DO 


CO 


oo 


r— 1 


OS 


Ir- 


>o 


CO 


H 


oo 


CO 


"# 


Ol 


© 


X 


CO 


, 1 


to 


on 


(M 


CO 


o 


CO 


i— 


,— 1 


«o 


on 


Ol 


CO 


o 


Ttl 


1— 


r-4 


rti 


os 


O0 


CO 


© 


CO 


to 


CO 


C- 


C- 


CO' 


CO 


CO 


OS 


OS 


OS 


Q 


o 




1 — 1 


^ 


Ol 


Ol 


Ol 


CO 


oo 


-* 


CO 


T* 


Ol 


O 


Q0 


CO 


-fl 


Ol 


OS 


t- 


LO 


00 


1— 1 


OS 


t~~ 


Tf( 


Ol 


© 


X 


CO 


-P 


CN 


-* 


OS 


Ol 


to 


rrs 


oo 


I-- 


, — 1 


tH 


.X) 


Ol 


to 


o 


CO 


t — 


, — 1 


LO 


X 


Ol 


CO 


© 


Tf 


o 


kQ 


33 


to 


to 


r> 


IT- 


00 


CO 


CO 


OS 


OS 


o 


o 


o 


^ 


JZi 


r—i 


Ol 


Ol 


CO 


CO 


X' 


CO 


tH 


<N 


o 


'CO 


CO 


-* 


^H 


OS 


t- 


LO 


CO 


1—1 


as 


CO 


-n 


Ol 


© 


X 


CO 


•>* 


, 1 


ro 


to 


CO 


r— 


© 


tH 


CD 


Ol 


o 


OS 


CO 


r- 


r— 1 


TfH 


-o 


Ol 


LO 


© 


CO 


r— 


^_i 


kO 


iQ 


o 


CO 


CO 


t> 


t- 


t- 


oo 


CO 


CO 


OS 


OS 


o 


o 


© 


J^ 


JZJ 


Ol 


Ol 


Ol 


CO 


CO 


,_, 


OS 


IT- 


kO 


oo 


,_, 


OS 


CO 


-* 


Ol 


o 


X 


CO 


-H 


,_ 


■as 


r— 


LO 


CO 


^ 


© 


m 


_H 


ro 


o 


rr 


no 


Ol 


LO 


OS 


CO 


r^. 


T—< 


-tl 


an 


Ol 


rO 


OS 


Ol 


r- 


,_< 


lO 


X 


^ 


o 


kO 


■CO 


CO 


to 


IT- 


t- 


b- 


X 


X 


OS 


OS 


OS 


o 


© 


© 


1 — 1 


i—i 
i—i 


Ol 
1—1 


Ol 


Ol 


^H 


as 


t- 


iO 


00 


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OS 


r— 


"<# 


Ol 


o 


CO 


CO 


^ 


Ol 


■as 


I-- 


LO 


00 


,H 


© 


t- 


t — 


, i 


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CO 


(M 


f o 


CO 


-o 


h- 


T— 1 


o 


<-n 


OJ 


CO 


8 


CO 


t— 


© 


kO 


as 


Ol 




<tf 


o 


o 


o 


CO 


CO 


to 


I- 


L— 


X 


co 


an 


OS 


os 


o 


© 








Ol 


Ol 






























I— 1 


1-1 


1-1 


1—1 


1-1 


r^ 


1-1 


1-1 


Ol 


o 


X 


o 


<CH 


(M 


© 


■CO 


LO 


CO 


I— 1 


en 


ISi 


lO 


00 


© 


X 


CO 


rH 


Ol 


© 


X 


O 


oo 


CN 


CO 


o 


rri 


oo 


1— 1 


lO 


OS 


CO 


CO 


o 


fh 


cr, 


Ol 


LO 


X 


co 


r- 


T— 1 




rtf 


•*# 


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kO 


CO 


CO 


co 


t- 


It- 


t- 


CO 


X 


OS 


as 


as 


o 


o 


© 


r— 1 


. — i 


Ol 

1 — 1 




CO 


rt* 


(N 


o 


OO 


CO 


tH 


CN 


OS 


r- 


LO 


CO 


,_ 


as 


ir- 


-H 


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© 


X 


CO 


rH 


CN 


00 


1— 


, — i 


o 


00 


CN 


to 


o 


oo 


i— 


1—1 


iO 


m 


Ol 


CO 


© 


CO 


r— 


, 1 


>o 


.oo 


CO 


"* 


t* 


lO 


LO 


kO 


CO 


CO 


IT- 


t- 


t- 


00 


CO 


X 


as 


as 


o 


© 


© 


^ 




1 — 1 


CN 


00 


,_, 


OS 


it— 


kO 


CO 


,-H 


OS 


co 


tH 


<M 


o 


X 


o 


Tji 


T^ 


o 


i— 


LO 


CO 


r-< 


OS 


Ol 


CO 


OS 


00 


h- 


1 — 1 


o 


oo 


fN 




o 


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l~- 


1 — 1 


iO 


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■01 


CO 


r> 


r^ 


m 


,_l 


^n 


<* 


-* 


LOj 


kO 


CO 


CO 


CO 


t- 


t- 


X 


X 


X 


as 


os 


as 


o 


© 


r— 1 

i—l 






CN 


00 


M 


OS 


IT~ 


kO 


CO 


^ 


OS 


CO 


tH 


CM 


o 


X 


CO 


■<* 


i—i 


as 


t- 


LO 


CO 


^ 


© 


,_l 


.--0 


CO 


Ol 


CO 


© 


-H 


r— 


, 1 


o 


as 


oo 


CO 


o 


-ti 


X 


, i 


lO 


.-o 


00 




o 


«tf 


"* 


■<* 


O 


O 


CO 


CO 


CO 


r- 


t- 


IT- 


X 


X 


as 


CO 


as 


© 


© 


© 






CN 


CO 


<* 


CN 


o 


CO 


CO 


tH 


oi 


CS 


(> 


L0 


CO 


^ 


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IT- 


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© 


CO 


CO 


-* 


CN 


o 


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on 


CN 


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OS 


CO 


t— 


o 


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X 


Ol 


CO 


m 


co 


i— 


, 1 


LO 


X 


Ol 


CO 


© 


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^ 


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lO 


LO 


CO 


CO 


t- 


it- 


it- 


oo 


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as 


CO 


© 


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CN 


o 


da 


b- 


lO 


CO 


H 


OS 


it- 


tH 


cm 


CD 


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CO 


-* 


CN 


as 


t— 


LO 


oo 


M 


as 


t- 


1—1 


CO 


r- 


^H 


o 


OS 


Ol 


co 


o 


Tfl 


CO 


r-i 


o 


OS 


co 


CO 


© 


tH 


X 


Ol 


»o 




<* 


<* 


tp 


o 


lO 


LO 


CO 


CO 


t- 


t- 


t- 


X 


X 


X 


as 


as 


o 


© 


© 




i-H 




o 


CO 


CO 


■<* 


CM 


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■CO 


CO 


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I— 1 


OS 


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LO 


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i—i 


X 


CO 


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Ol 


© 


co 


CO 


T* 


r— 


T— 1 


iQ 


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CO 


o 


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oo 


, — 1 


LO 


os 


00 


i— 


© 


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00 


Ol 


CO 


as 


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00 


CO 


«* 


-& 


<* 


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LO 


CO 


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l> 


t- 


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d 


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d 


d 


d 


d 


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d 


d 


d 


d 


d 


© 


d 


d 


d 


d 


r*» 


d 


© 


OS 


o 




CN 


O.I 


^n 


LO 


so 


1 - 


an 


os 


o 


!—) 


CN| 


oo 


tH 


lO 


to 




on 




o 
























CN 


f.N 


CN 


CN 


CN 


CN 


Ol 


Ol 


M 


M 


CO 



INDEX 



THE FIGURES BELOW REFER TO THE NUMBERS OF THE PAGES. 

Absolute pressure, 13. 

Accidents to locomotives, 509. 

Accidents and injuries to persons, 533; danger from, 535. 

Actual energy, 24. 

Adhesion, 62, 319 ; amount of, 320 ; proportion of to resistance, 412. 

Adhesive weight, 321. 

Admission, depends on, 222 ; how affected, 255; how equalized, 249; oi 
steam, 30 ; period of, 249. 

Admission line, 236, 237. 

Air, admission of to fire-box, 380; control of supply of, 384; forces of, 8; 
method of admitting to the fire-box, 382; pressure of, 8, 9; quan- 
tity necessary for combustion, 381, 388; quantity needed for dilu- 
tion of gases, 389 ; quantity to be admitted through the grate and 
above the fire, 391; weight of, 8. 

Air chamber, 117. 

Alarm check, 126. 

Algebra, x. 

Algebraic symbols, x. 

Allen valve, 224. 

American locomotive, 429; engraving of, 555, 557, 559. 561, 563. 

American Railway Master Mechanics' Association, 260, 288. 

Angular advance, 251. 

Animal oil, 504. 

Anthracite coal, 112. 152, 403; firing with, 503. 

Aquafortis, 368. 

Argand-burner, 336. 

Arterial bleeding, 536. 

Artery, 536; injury to, 537, 539; position of, 537. 

Ash-pan, 67; construction of, 81. 

Ash-pan dampers, 81; operation of, 153. 

Atmospheric line, 48. 

Automatic brakes, 442; management of. 495. 

Axle, adjustment of, 475; breaking of, 509, 523; how made to assume a 
radical position, 278. 282 ; main driving, 63. 

Axle box, arrangement of, 296; bearing of, 290; driving, 290; for ten- 
ders, 355; wear of, 297. 

Babbitt's metal, 173, 175, 180. 

Back elevation, xiv. 

Back pressure, 56, 163; line of, 236,243. 

Back view, xiv. 

Backward motion or gear. 187. 

Baldwin Locomotive Works, 429; locomotive by, 555, 565, 567. 

Ball joint, 160. 

Bearings, brass, 177 ; for driving axles, 290; for tender axles, 354; foi 

trucfcraxles, 292 ; proportions of, 362 ; wear of, 179. 
Bearing-bars, 152. 



■■■■■ 






Index. 599 



Bed-casting. 164. 

Bed- plate, 146. 

Bell, 335; use of, 479. 

Bissell truck, 432. 

Bituminous coal, 368; composition of, 369, 388 ; use of, 503. 

Blast orifice, 71; (see also exhaust nozzle). 

Bleeding, danger from. 535; stopping of, 537, 540. 

Blower, 149; use of, 480. 

Blower cock, 149. 

Blow-off cock. 148. 

Bloclc, link, 185; (see liuk block). 

Boiler. 66, 71; advantages of large size, 422; calculations of, 419; capac- 
ity of. 71. 418; cleaning of, 147. 505; emptying of, 147; expansion 
of. 90. 295, 478; explosion of, 509, 514; feeding of, 483; filling of, 
506; inspection of, 461; irregular action of, 421 ; organs of, 66; ope- 
ration of, 420; proportions of, 419; size of, 417, 420; strains on, 
85,478; testing of, 461. 

Boiler attachments. 115; examination of, 465. 

Boiler plate, fastenings of, 90 ; resistance of, 95 ; strength of, 89, 95 ; un- 
equal strain on, 92. 

Boiler pressure, 223; difficulty of maintaining in cylinders, 223. 

Boiler seams, form of, 103; strength of, 93, 106. 

Boiling. 10. 

Boiling point, 11. 

Bones, injury to, 542. 

Books, list of, 550. 

Boss, 207. 

Boxes, for driving axles, 290; for tender axles, 355; for truck axles, 292. 

Braces, 80, 107; for frames, 292; proportions of, 108. 

Brakes, continuous train, 442; for tenders, 356; inspection of, 475; re- 
liance on, 494. 

Brass bearings. 177; (see bearings). 

Brasses, 177. 

Breaking joints, 173. 

Bridges, 31 ; width of, 260. 

Buchanan, William, see preface, 402. 

Bumper-timber, 292. 

Bunsen burner, 374. 

Burns, treatment of, 542. 

Bushing, 174, 180. 

Butt-joints, 106. 

Cages, 116. 

Candle, 375 ; flame of, 375. 

Carbon, 369, 371; air required for combustion of, 388; total heat of com 

bustion, 380. 
Carbonic-acid gas 378. 
Carbonic dioxide, 378. 
Carbonic oxide, 378. 
Carburetted hydrogen, 369. 
Carrying wheels, 268. 
Cars, resistance of, 406. 
Casing, for cylinders, 170. 
Caulking, 106; effect of, 107. 
Caulking edge, 106. 

Centre bearing, 356 ; lubrication of, 475. 
Centre of gravity, calculation for, 329, 330, 331. 
Centre-pin, 2^9, 271, 316. 

Centre-plate, lower, for truck, 316; lubrication of, 475 ; upper, 316. 
Check-chains, 340, 350. 

Check-valve, failure of, 509, 518; for injector, 120; for pump, 1x7. 
Chemical element, 365 ; combination of, 366. 
Chemical equivalent, 367. 



600 Index, 

Chilling, 291. 

Chimnev, 66; construction of. 112. 

Clearance, of piston. 221; effect of, 228; of valve, 42. 

Coal, amount of water evaporated by, 73, 394; condition of when put 
on fire, 387 ; value and properties of. 594. 

Cock, blower, 149; blow-off. 148: cylinder. 171: feed. 119; frost, 119- 
gauge, 130; heater. 149; oil, 169; pet, 118; try, 130. 

Co-efficient of friction. 359. 

Coke, 379; air needed for combustion of, 392. 

Cold weather, 496. 

Color blindness, 493. 

Collision. 509 ; prevention of, 510. 

Combustion. 365; air required for, 380. 388; chemical process of. 379; 
effect on of enlarging the grate, 392; how explained, 370: in loco- 
motive fire-box, 377: intensity of, 393; in tubes, 386; products of, 
378; rate of, 73, 365; total heat of, 380. 393: when complete, 373. 

Compression, 44, 221; calculation of, 243; effected by, 228 ; efi'ect of. 247 ; 
line or curve of, 236. 

Compressive strain, 89. 

Combining tube, 31. 

Condensation. 17. 

Conduction, 18; of heat through heating surfaces. 395. 

Cone, 112; cone of wheel, effect of, 274, 277: advantage of. 2S5. 

Connecting-rod, 5, 164; angularity of. 45, 175; breaking of. 509; con- 
struction of, 177; effect of. 44; inspection of, 467, 471; main, 177 ; 
pressure of, 174 ; wear of, 177. 

Consolidation locomotive, 430, 569. 

Continuous train brakes, 442, 

Convection, 111,118. 

Counterbalance weights, (see counterweights.) 

Countersunk joint. 156. 

Counterweights. 289, 328; calculation for, 328, 331, 333; construction of. 
333. 

Coupling, breaking of, 510, 531; engine to tender, 480. 

Coupling-pin, 350. 

Coupling-rod, 177; why taken down, 523. 

Covering strip. 100, 103. 

Cow-catcher, 294. 338. 

Crank, 5. 63. 

Crank-pin. 64; breaking of, 509, 522; construction of, 288; how fastened, 
23^ : inspection of, 463 ; pressure on, 244. 

Creamer's brake, 442. 

Crow-feet, 107. 

Cross-head, 174; accident to. 509; inspection of, 471. 

Crossing, approach to, 493, 511. 

Crown-bars, SO. 

Crown-sheet, or crown-plate. 75. 80. 

Crushing. 95, 98; treatment of, 542. 

Curye, degree of, 410; resistance on, 410; running through, 4S9. 

Curve of compression. 236. 

Curve of expansion, 236. 

Cut-off, 16, 41; advantage of, 4S3; effect of link on, 217; effect of throw 
of eccentric on, 252. 

Cushion, 38. 230. 

Cylinder, 163,164; breaking of, 509, 521; construction of, 164; distance 
between. 69; inspection of, 63; location of, 63; protection of, 170: 
size of, 69, 413. 

Cylinder capacity, 414 ; calculation for, 415, 416. 

Cylinder casing, 170. 

Cylinder cocks, 171 ; use of, 479. 

Cylinder-heads, 165 ; breaking of, 521. 

Cylinder-head covers^lTO. 

Cylinder lagging, 170. 



Index. 601 



Dampers, for ash-pan, 81. 153. 

Danforth Locomotive and Machine Co.. 429; locomotive by, 559, 569. 

Dangers to which locomotive runners are exposed, 544. 

Dead-point, 5. 

Dead- grate, 387. 

Deflector, for tire -box door, 400; for sparks, 112. 

Delivery-tube. 120. 

Diaphragm, 140. 

Different kinds of locomotives. 427 

Dilution of gases, air needed for, 389. 

Distribution of steam, 220; defects of, 248; effect of, 231. 

Distribution of weight, on driving wheels, 413. 

Dome, 110; location of, 110. 

Double-end tank locomotive, 571, 573, 581. 

Double poppet valve. 155. 

Double truck locomotive, 435, 577, 579. 

Draft. 67, 72. 

Draw-bar, 334. 

Draw-bridge, approach to, 493 ; running into, 509, 511. 

Drawings, xiii. 

Drilled holes, 92. 96, 98, 103. 

Drilling cars, 427. 

Drip-pipe, 132. 

Driving-axle, breaking of, 523; main. 70; (see also axle). 

Driving-axle boxes, 290; bearing of, 290. 

Driving-wheels, 70, 268; action of, 323; adhesion of, 62, 319; breaking of, 
523; construction of, 285; distance between, 68; effect of their 
size on combustion and evaporation, 424; friction of, 62, 319; how 
fastened, 288; motion of around curves 284; relation between 
size of and that of boiler, 425; size of, 68, 413, 425; weight on, 69. 

Drop-door. 153. 

Dry-pipe, 111. 

Duplicate parts, 477. 

Dust guard, 356. 

Ebullition, 11, 485. 

Eccentric, 6; effect of throw of, 252, 255; how set, 1S2; 528; motion how 
communicated to valve. 185; motion same as that of crank, 31; 
slipping of, 526, 528; throw of, 31, 251; with varying lap, 258. 

Eccentric-rod, 7; breaking of, 527. 529. 

Eccentric-strap, 6; breaking of, 529. 

Effective pressure, 14. 

Eight-wheeled American locomotive, 555, 557, 559, 561, 563. 

Ejector, 446. 

Elasticity, limit of, 89, 302; of spring, 302. 

Klastic strength, of spring. 302. 

P^lementary suhstances, 365. 

Energy, 22, 23; actual, 24,29; of repulsion, 28; possible or potential, 28. 

Endurance, 545. 

Equalizing lever, 309; advantages of, 313; breaking of, 509, 525; con- 
struction of, 310; distribution of weight by. 310; of truck, 318. 

Evaporation, amount required, 72; latent heat of. 26. 

Exhaust of steam. 30, 67; how affected by link, 217, 249. 

Exhaust line, 236, 242. 

Exhaust-nozzle, 68, 71. 

Exhaust passage, 165. 

Exhaust pipe, 162. 

Exhaust-port, 5; width of, 260. 

Exhaust steam, action of, 71, 72. 

Expander, 84. 

Expansion, 16, 221; advantages of, 55, 60, 482; limits of economy, 60- * 

Expansion clamps, 294. 

Expansion curve or line, 51. 



602 Index. 

Experiments with locomotives, 450. 

Explosion of boiler, 509; cause of, 514; prevention of, 516. 

Fairlie engine, 435. 

Feed-cock, 119, 149. 

Final pressure. 56, 482. 

Fire, depth or thickness of, 383; management of, 500; method of feed- 
ing, 383 ; method of starting, 478. • 

Firing, 499, 501. 

Fire-box, 66, 67; construction of, 75; expansion of, 479; form of, 397; 
size of, 69. 

Fire-brick arch, 397. 

Flame, length of, 376; nature of, 371, 375. 

Flange of wheel. 278; friction of, 281. 

Flue, 66, 67; arrangement of, 81; bursting or collapse of, 509, 516; fas- 
tening of, 83. 

Flue expander, 84. 

Flutter of water, 487. 

Fly-wheel, 5. 

Foaming. 484; cause of, 486; effect of, 488; prevention of, 486. 

Follower bolts, 172. 

Follower plate, 172. 

Foot-board or plate, 261, 338; effect of weight of, 339. 

Foot pound, 23. 

Force-pump, 115. 

Forney locomotive, 434, 575. 

Forward motion or gear, 187. 

Four-wheeled locomotive, 428; disadvantages of. 428; engraving of, 553. 

Frames, 65, 292; attachment to the fire-box, 295; breaking of, 510, 526; 
fastening of, 294. 

Franklin Institute, system of screw threads, 342. 

Freezing of water in boiler, 507 ; in pumps, 119, 507, 532. 

Freight locomotive, 429. 

Freight traffic, 427, 429. 

Friction, 358 ; depends on, 358 ; co-efficient of, 359 ; effect of pressure 
and velocity of surfaces on, 361 ; effect of area of surfaces in con- 
tact, 364; lav of, 363; of wheel flanges, 281; of wheels, 62, 319. 

Front view, xiv. 

Front elevation, xiv. 

Frost-bite, treatment of, 543. 

Frost-cock, 119. 

Fuel, value of, 4C , waste of, 394. 

Fulcrum of drivi .g wheel. 312. 

Furnace door, 67, 80, 149. 

Gas, 368 ; combustion of, 376. 

Gas-light, 371. 

Gauge of road, 75. 

Gauge-cocks, 130. 

Gibs, 175. 

Gland, 173. 

Glass water-gauge, 130 ; inspection of, 465. 

Grades, effect of on water level, 491; resistance on, 408; running on, 

490. 
Grant Locomotive Works, 429; locomotive by, 557. 
Grate, 67, 73, 81, 149; dead, 387; inspection of, 465; management of, 504, 

506; rocking, 152; shaking, 152; surface, 419; water, 152. 
Grate-bars, 150. 

Greenwich Street Elevated Railroad, 441. 
Guide-blocks, 176. 

Guide-rods or bars, 164; inspection of, 467; object of, 174; wear of, 176. 
Guide-yoke, 175. 



Index. 603 



Half-gear, 195. 

Hand-holes, 148. 

Hand-rails, 337. 

Head-light, 336; inspection of, 476; use of, 495. 

Heat, conduction of, 74: convertible into work, 25; equivalent of, 24; 
latent, 26; loss of 395; mechanical equivalent of, 22; total of, 
steam, 29, 585; transmission of, 381, 395, 423; waste of, 18, 395. 

Heater-cocks, 149 ; use of, 486. 

Heating surface, 67; amount needed. 73, 419, 420. 

Heat of evaporation or gasification, 369. 

Helper, 497. 

Henderson's brake, 442. 

Hinkley Locomotive Works, 429; locomotive by, 553, 563. 

Hood for fire-box door, 400. 

Horizontal section, xiv. 

Hose, 350. 

Hudson River Railroad, locomotives used on, 440. 

Hydrogen, 369, 371; air required for combustion of, 388. 

Hyperbolic curve, 51, 237. 

Hyperbolic logarithms, 54; table of, 590. 

Hyponitrous acid, 368. 

Igniting; temperature, 370, 376; of coal gas, 387. 

lncrustating substances. 454. 

Indicator, steam, 47, 231; method of attaching, 234. 

Indicator, diagram, 51, 233; form of, 235, 240, 241,247. 

Induced current, 374. 

Initial pressure, 60. 

Injector, 120; action of, 120; action of fixed nozzle injector, 123; action 
of hot water on, 123; fixed nozzle, 120; failure of, 509, 518; inspec- 
tion of, 465 ; location of, 127 ; self- regulating, 124. 

Injuries to persons, 533. 

Insensibility, treatment of, 541. 

Inside pipe, 113. 

Inspection of locomotives, 461. 

Intensity of combustion, 393. 

Internal disturbing forces, 328. 

Introduction, ix. 

Inverted plane, xv. 

Jauriet, C. F. ; water tables, 399. 

Jaws, 292. 

Johnson, "Walter B., experiments on coal, 405. 

Journal. 177; effect of increased diameter, 362; heating of, 504; oiling of 

179; of driving axle. 290; of truck axles, 292. 
Journal bearing, of driving axle, 290; of tender axles, 351; of truck 

axles, 354. 

Keys, 179. 

Lagging, 111 ; for cylinders. 169. 

Lamp, 373: for head-light. 336, 376. 

Lap, 40, 251 ; inside. 40; effect of, 41 ; outside. 40; effect of, 41, 44; effect 

of reducing, 255; effect of varying, 258. 
Latent heat. 26; of evaporation, 26, 29. 
Lateral motion, 317, 430. 
Laughing gas, 368. 
Lead, 38, 220, 249, 253; cause of, 218; effect of, 44; how affected by linfc, 

218; how equalized, 249; inside, 38; necessity for, 221. 
Lift of pump valves, 117. 
Lifting arm, 66; breaking of, 529. 
Lifting shaft, 185; breaking of, 530; position of, 250. 
Limit of elasticity, 89 ; of spring, 302. 



604 Index. 

Line and line, 237. 

Linear advance, 252. 

Line of back-pressure, 236, 243. 

Line of compression, 236. 

Line of expansion, 236. 

Liners, 175. 

Link, 66, 185 ; motion of, 189 ; radius of, 200. 

Link-block, 185. 

Link-hanger, 185, 250; breaking of, 529. 

Link motion, 181, 196, 248. 

Link-saddle, 187 ; breaking of, 529. 

List of books, 550. 

Live steam, 229. 

Locomotive, 62; advance of. 323; capacity of, 421; cleaning and repair- 
ing of, 505; cost of operating, 448; different kinds, 427; dimen- 
sions of, 68, 429; escape of, 509, 511 ; experiments with, 450; gener- 
al description of, 62 ; how turned around, 455; inspection of, 461; 
list of parts of, 69; number of miles run to a ton of coal, 449; 
principal parts of, 62; proportions of. 412; resistance of, 62; speed 
of, 419; starting of, 480; weight of, 67. 

Longitudinal section, xv. 

Lost motion, 180. 

Loughridge's brake, 442. 

Lubricant, 360; manner of applying, 360. 

Lubrication, 358; effect of pressure and velocity of surfaces on, 361; 
method of, 477. 

Man-hole, 349. 

Mason Machine Works, 429, 436; locomotive by, 561, 577, 579. 

Mason, William. 435. 

Master Mechanics' Association. 260. 288. 

Mechanical equivalent of heat. 22. 

Metropolitan railroads, 427, 437; locomotives for, 436, 438, 440. 

Mid-gear, 195. 

Miles run to ton of coal, 449. 

Mineral oil, 504. 

Miscellaneous, 335. 

Model of valve-gear, 204. 

Modulus of propulsion, 415. 

Mogul locomotive, 430. 567. 

Molecular activity, 376. 

Momentum of piston, 230, 244; creates resistance to turning of crank, 

216. 
Motion, reciprocating, 5; rotary, 5. 
Motion curves, 34, 196; how drawn, 197, 204, 208. 
Motion diagram, 213, 214. 
Mud-drum, 148. 
Mud-holes, 148. 

New York elevated railroad, 441 ; locomotive for, 583. 

Nitric acid, 368. 

Nitrogen, 368. 

Nitrous acid, 368. 

^Nitrous oxide, 368. 

Nuts, 341 ; proportions of, 348. " 

Oil, 360; animal, 504; manner of applying, 360; mineral, 504. 

Oil boxes, for tender, 354. 

Oil cellars. 179, 290. 

Oil-cock, 169. 

Oil-cup, 176. 

Open-road, 428; running on, 489. 

Operating locomotives, cost of, 448. 



Index. 60^ 



Outside shell of fire-box, 75. 
Overflow, 120. 
Overflow-nozzle, 121. 
Oxalate of ammonia, 454. 
Oxygen, 368, 370. 

Packing, 173. 

Packing-bolts, 173. " 

Packing-nuts, 132, 173. 

Packing-rings, 172; inspection of, 468 ; setting out, 469. 

Packing-springs, 172. 

Parabolic reflector, 337. 

Parallel motion. 233. 

Parallel-rods, 177. 

Passenger traffic, 427 ; locomotive for, 436. 

Perforated pipe, 488. 

Performance and cost of operating locomotives, 448. 

Periods of distribution of steam, 220. 

Periphery of wheel, 277. 

Pet-cock, 118, 149. 

Petticoat-pipe 113. 

Pile-driving machine, 28. 

Pilot, (see cow-catcher,) 294, 33 s !. 

Piston, 1; accident to, 509, 522; diameter of, 69, 164, 416; construction 
of, 172 ; how oiled, 169 ; inspection of, 467 ; momentum of, 33, 230, 
241; stroke of, 416. 

Piston-heari, 172. 

Piston-rod, 2; action of, 174; breaking of, 509 ; construction of, 171. 

Pitch of screw-threads, 341, 343. 

Plan, xiv. 

Plates, 551. 

Potential energy, 24, 28. 

Pre-admission, 197, 220, 237, 240. 

Preface, iii. 

Pre-release, 221, 226, 249. 

Pressure-valve, 115. 

Priming, 170, 484; cause and prevention of, 486; effect of, 488. 

Properties of saturated steam, table of, 585. 

Proportions of locomotives, 412. 

Prosser's expander, 84. 

Pump, 115; construction of, 115; failure of. 509 518; freezing of. 120, 507, 
532; inspection of, 466; location of, 119; regulation of, 119; work- 
ing of 176; in a snow storm, 532. 

Pump-barrel, 115. 

Pump-lug, 177. 

Pump-plunger, 155, 177. 

Pump-valve, 115. 

Punched holes, 9, 93, 103. 

Punching holes, 91, 93. 

Pushing-bar, 338. 

Pyrometer, 397. 

Quadrants, 261. 

Radiation, 18, 111 ; from boiler, 397. 

Haiti storm, running in, 497. 

Receiving-tube, 120. 

Reciprocating motion, 5. 

Reflector, 337. 

Release of steam, 41, 221 ; governed by, 227; how affected by link, 217. 

Repulsion of particles, 28. 

Requirements and duties of locomotive runners, 547. 

Reserve engine, 497. 



606 Index. 



Resistance of trains, 406; on curves, 410; on grades, 408; table of, 407, 

596. 
Responsibility and qualifications of locomotive runners, 544. 
Reverse-lever, 66, 187; breaking of, 530; construction and location of, 

261 ; length of, 263. 
Reverse-rod, 187, 261; breaking of, 530. 
Reversing gear, 264. 
Richardson safety valve, 140. 
Richard's steam engine indicator, 231. 
Riveted seams, 91; strength of, 93, 65, 106. 
Riveting, chain, 100; double, 100; machine, 97; single, 95; strength of, 

103 ; strongest form of, 99. 
Rivets, 90; arrangement of, 91; crushing of, 95, 98; diameter of, 98; 

proportions of, 91; shearing of, 94; staggered, 101; strength of, 

94 ; zigzag, 101. 
Rocker, 7 ; accident to, 529. 
Rocker-arm, breaking of, 529; length of, 204. 
Rocker-pin, 185. 
Rocking grate, 152. 

Rogers Locomotive Works, 402, 571, 573. 
Rotary motion, 5. 
Running-board, 337. 
Running-gear, 268; inspection of, 473. 
Running locomotives, 478. 
Running off the track, 509, 512. 
Russia iron, 111. 

Saddles, 296. 

Safety chains, 340, 350. 

Safety-valve, 134; effect of blowing off, 485; inspection of, 465; pressure 
on, 136 ; Richardson's, 140. 

Safety-valve lever, 135. 

Safety-valve seat, 139. 

Sand box. 335; use of, 481. 

Saturated steam, 13; properties of, 585. 

Scalds, treatment of, 542. 

Scale, 453. 

Screw-threads. 341; form of, 343; proportions of, 345; system of, 342; 
table of, 348. 

Seams, riveted, 91; strength of, 95. 

Section, xiv. 

Sectional view, xiv. 

Sectors, 261; arrangement of notches in, 263. 

Sellers, William, 342; system of screw-threads, 342, 344. 

Sellers, William & Co., turn table by, 456. 

Setting out packing, 469. 

Set-screws, 179. 

Shaking grate, 152. 

Shearing, 94, 98. 

Shock, treatment of, 541. 

Shoes, 297. 

Shunti.ig, 427. 

Side-bearing, 356. 

Side elevation, xiv. 

Side rods, 177. 

Side view, xiv. 

Signals, 447 ; observance of, 481, 489, 493. 

Slack of the train. 481. 

Slides, 174; how oiled, 176; wear of, 175. 

Slide-valve, 6, 30; advance of, 38; conditions which it must fulfill, 30; 
disadvantages of first form of, 37; first form of, 30; how made 
steam tight, 169; inspection of, 472; lap of, 40; middle position of, 
184; motion of modified by the proportions of link motion, 248; 
oiling of, 169, 492; proportions of, 260; setting of, 264 ; travel of, 88. 



Index. 607 



Smith, A.F., 441. 

Smith's vacuum brake, 442. 

Smoke, 368 ; cause of, 372 ; prevention of. 503. 

Smoke-box, 66, 111; temperature in, £96. 

Smoke-stack, 66; construction of, 112; inspection of, 465; proportions 
of, 112 ; size of, 69. 

Snow, 497 ; melting of, 532. 

Snow storm, blockade by, 532; running in, 497. 

Sobriety, importance of, 545. 

Soot, 371. 

Spacing rivets, 96, 98. 

Spark deflector, 112. 

Speed of locomotives, 450. 

Spherical joints, 160. 

Spider, 172. 

Spread of wheels, 285. 

Spring, 295, 297 ; breaking of, 509. 525 ; construction of, 297 ; curvature 
of, 301, 307; elasticity of, 297,303, 306; necessity for, 295; numbel 
of plates of, 306; proportions of, 304; span of, 306; strength of, 
303. 

Spring balance, 137. 

Spring balance lever, 138. 

Spring hanger, 297; attachment of, 308; breaking of, 509. 

Spring strap, 300. 

Staggered rivets, 10] . 

Starting- valve, 126. 

Stations, running into, 494; running past, 492; stop at, 503. 

Stay-bolts, 76; breaking of, 79, 463; strain on, 78. 

Steam, 10 ; absolute pressure of, 13, 585 ; admission of, 30, 155 ; advantages 
of using expansively, 55; application of, 1; condensation of, 17; 
cut-off,"4l; effective pressure of, 14; exhaust of, 30; expansion of, 
14, 41, 47; expansive force of, 1; generation of greatest amount of, 
500; pressure in cylinders, 47,52, 53, 223; pressure, limit of, 134; 
pressure of, 11; pressure of after expansion, 16; properties of, 56, 
585; quantity required, 420; release of, 41; saturated, 13; super- 
heated, 13 ; total heat of, 29, 57, 585 ; temperature of, 585 ; weight 
of, 585 ; volume of, 14, 163, 585 ; wire drawn, 59. 

Steam-dome, 110; location of, 110. 

Steam-chest, 6; bursting of, 509, 522; construction of, 169; protection of, 
170. 

Steam-chest cover, 169. 

Steam-gauge, 140; connection of, 145; inspecting of, 465; testing of, 145. 

Steam indicator, 231; method of applying, 234. 

Steam line, 236. 

Steam passage, 165. 

Steam pipes, 111, 155; bursting of, 509, 522; construction of, 158. 

Steam ports, 5 ; opening of, 217. 

Steam space, 109. 

Steam ways, 5, 122; effect of, 228 

Steam whistle, 146. 

Steel plates, 479. 

Straps, 177. 

Stroke, 16. 

Stub-end, 179. 

Studies for mechanics, locomotive runners, &c, 549. 

Stuffing-box, 173; inspection of, 470. 

Suburban railroads, 427 ; locomotives for, 436, 438. 

Suction-pipe, 115. 

Suction- valve, 115. 

Sun stroke, treatment of, 543. 

Superheated steam, 13. 

Surface-cock, 487. 

Suspending-link, 250. 



608 Index, 

Suspension, point of, 249. 

Suspension-links, 318. 

Switch, 269. 

Switching locomotive, 427, 428; running of, 499; engraving of, 553. 

Tangent, 209. 

Tank, 68, 349; capacity and weight of, 69, 346, 359; how strengthened, 
350. 

Tank locomotive, 428, 432, 571, 573, 575, 577, 579, 581, 583. 

Taunton Locomotive Manufacturing Company, 428. 

Temperature in tire-box, 387; necessary to ignite coal gas, 387. 

Tender,68; capacity and weight of, 69, 349, 357; construction of, 349. 

Tender trucks, 350, 356. 

Tender-valve, 350. 

Tensile strain, 89. 

Ten-wheeled locomotive, 430, 565- 

Testing of boilers, 461 ; of steam gauges, 145. 

Threads (of screws); see screw-threads, 341. 

Three-legged principle, 317. 

Throttle-pipe, 111. 

Throttle- valve, 155; failure of, 510, 530; inspection of, 466; operation of. 
158; use of, 481. 

Throttle- valve lever, 158. 

Throw of eccentric, 31. 

Thumb tool, 84. 

Tires, 63, 285; breaking of, 509, 424; how fastened, 286; standard size of, 
288. 

Tools for engine, 476. 

Top view, xiv. 

Total heat of combustion, 380, 393; of steam, 29, 57. 

Total pressure of steam, table of, 585. 

Tourniquet, 537- 

T pipe, 159. 

Traction, 319. V 

Tractive power, 321. 

Traffic, freight and passenger, 427. 

Trailing wheels, 65; breaking of, 524. 

Train, protection of, 514. 

Transverse section, xv. 

Travel of valve, 38; effect of changing, 42, 195, 214, 216; how changed, 
187. 

Tread of wheel, 277. 

Truck, 268; construction of, 314; effect of on movement of locomotive 
around curves, 273; for tender, 356 ; lateral motion of, 317, resist- 
ance to rolling, 280; use of, 269; with single pair of wheels, 271, 
430. 

Truck axle, 280 ; breaking of, 524. 

Truck boxes, 292, 314. 

Truck frame, 314. 

Truck springs, 314. 

Truck wheels, 65, 268; breaking of, 524; construction of, 291', size of, 
68 ; slip of, 273 ; weight on. 69 ; why two are used, 269. 

Truss-bars, 316. 

Try-cocks, 130. 

Tubes, 66; arrangement of, 81; bursting or collapse of, 509, 516; fasten- 
ing of, 83 ; number and size of, 69, 74. 

Tube-expander, 84. 

lurn-table, 451 ; construction of, 455. 

Unguent, 360. 

Ultimate strength, 90 ; of springs, 302. 

Unit of heat, 58. 

Unit of work, 23. 

United States standard for screw-threads, 343, 



Index. 609 

Va cuum brake, 442 ; construction of, 446. 

Vacuum line, 48. 

Va lve, slide, G. (See slide-valve). 

V;ilve, Allen's, 224. 

valve-face, 40. 

Valve-gear. 181; construction of, 181; dimensions of, 216; injury to, 

510 ; inspection of, 472 ; model of, 250. 
Valve-rod, 7. 
Valve-seat, 5. 

Valve-stem, 7; accident to, 529. 
Vapor, 10. 

Variable exhaust, 163. 
Venous bleeding, 536. 
Vertical section, xiv. 
Volume, 14. 

Wagon top, 109. 

Waist of boiler, 67. 

Ward's air brake, 442. 

Water, amount evaporated per pound of coal, 73, 394; -freezing of, 507 1 

height of in boiler, 130, 484; muddy, 486; "solid," 487; supply ex- 

hausted, 531. 
Water crane, 452. 
Water gauge, 130, 132. 
Water grate, 152. 
Water s[/Ace, 67 ; size of, 69, 75. 
Water supply, 453. 
Water table, 399. 

Water tank, effect of carrying weight of on driving-wheels, 433, 451. 
Wedges, 294, 297; bolts for. 475. 
Weight, distribution of, 413. 
Welt, 100, 103. 
Westinghouse brake, 442. 
Wheels, driving, 268; adhesion of, 62; breaking of, 509, 524; carrying, 

268; size of. 68; trailing, >; truck, 65, 268. 
Wheel-base, 69. 285. 
Wheel centres. 63," 286. 
Wheel guards, 340. 
Wild engine, 498. 
Wire drawn, 59, 197, 482. 
Wire netting, 465; method of cleaning, 466. 
Work. 22; convertible into heat, 25, 
Working water, 170. 
Wrist-pin, 175. 
Wyman, 1>. W., locomotive by, 583. 

Y, 460. 

Zigzag rivets, 101. 


















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